Bulletin  No.  324 


Series  R,  Structural  Materials,  1 


DEPARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

GEORGE  OTIS  SMITH,  Director 


THE 

SAN  FRANCISCO  EARTHQUAKE  AND  FIRE 

OF 

APRIL  18,  1906 

AND  THEIR  EFFECTS  ON  STRUCTURES  AND 
STRUCTURAL  MATERIALS 


REPORTS  BY 

GROVE  KARL  GILBERT,  RICHARD  LEWIS  HUMPHREY, 
JOHN  STEPHEN  SEWELL,  and  FRANK  SOULE 

WITH  PREFACE  BY 
JOSEPH  AUSTIN  HOLMES 

In  Charge  of  Technologic  Branch 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 

1907 


Digitized  by  the  Internet  Archive 
in  2016 


https://archive.org/details/sanfranciscoeartOOgilb 


CONTENTS, 


Preface,  by  Joseph  A.  Holmes 

The  Earthquake  as  a Natural  Phenomenon,  by  G.  K.  Gilbert 

Introduction 

The  fault  trace 

Cracks 

Dislocations  of  surface  material 

Motions  constituting  the  earthquake 

Distribution  of  intensity 

The  Effects  of  the  Earthquake  and  Fire  on  Various  Structures  and 

Structural  Materials,  by  Richard  L.  Humphrey 

General  discussion  of  the  earthquake  conditions 

Effects  on  structures  outside  of  San  Francisco 

Conditions  in  San  Francisco 

General  earthquake  conditions  and  effects 

Behavior  of  individual  structures 

General  statement 

Academy  of  Sciences  building 

HStna  (Young,  or  Commissary)  Building 

Appraisers’  warehouse  (United  States  custom-house) 

Aronson  Building 

Bekins  Van  and  Storage  Company’s  building 

Bullock  & Jones  Building 

California  Casket  Company’s  building 

Call  (Claus  Spreckels)  Building 

Chronicle  buildings 

City  hall  and  hall  of  records 

Crocker  Building 

Emporium 

Fairmount  Hotel 

James  Flood  Building 

Grant  Building 

Hotel  Hamilton 

Hibernia  Savings  and  Loan  Society’s  building 

Hobart  Building 

Jackson  Brewing  Company’s  building 

Hall  of  Justice 

Kamm  Building 

Kohl  (Hayward)  Building 

Majestic  Theater 

Mercantile  Trust  Company’s  building 


Page. 

XI 

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12 

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30 

31 

31 

32 

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34 

35 

35 

36 

36 

37 
37 

37 

38 
38 

38 

39 
39 

39 

40 
40 
40 


iii 


IV 


CONTENTS. 


The  Effects  of  the  Earthquake  and  Fire  on  Various  Structures, 
etc. — Continued. 

Conditions  in  San  Francisco — Continued. 

Behavior  of  individual  structures — Continued.  Page. 

Merchants’  Exchange  building ±. 41 

Mills  Building 41 

United  States  mint 42 

Monadnock  Building 42 

Murphy  Building 43 

Mutual  Life  Building 43 

Pacific  States  Telephone  and  Telegraph  Company’s  building_  43 

Post-office  building 44 

Rialto  Building 45 

St.  Francis  Hotel 45 

Scott  Building 46 

Security  Savings  Bank 46 

Shreve  Building x 46 

Sloane  Building 47 

Spring  Valley  Water  Company’s  building 47 

United  States  subtreasury 47 

Union  Trust  Company’s  building 47 

Volkman  Building 48 

Wells-Fargo  Building * 48 

Aspects  of  the  fire  disaster : 49 

Fire  history  and  recommendations  of  insurance  boards 49 

Fire-resisting  qualities  of  structures  and  structural  materials 51 

Water  supply  and  other  methods  of  fighting  fire 55 

General  lessons  of  the  earthquake  and  fire 56 

Obstacles  to  the  reconstruction  of  San  Francisco 59 

Statistics  and  general  information 60 

The  Effects  of  the  Earthquake  and  Fire  on  Buildings,  Engineering 

Structures,  and  Structural  Materials,  by  John  S.  Sewell 62 

Introduction 62 

Scope  of  the  investigation 62 

Acknowledgements 63 

Extracts  from  the  report  of  a committee  of  the  National  Board  of 

Fire  Underwriters  on  San  Francisco  conditions 64 

Some  features  of  the  earthquake  and  fire 66 

Amount  of  destruction  due  to  the  earthquake  and  fire,  respec- 
tively   66 

Fire-fighting  operations  ; the  use  of  dynamite 66 

Temperatures  of  the  Baltimore  and  San  Francisco  fires 68 

Earthquake-  and  fire-resisting  qualities  of  structures  and  structural 

materials  69 

Effect  of  fire  on  Government  and  class  A commercial  buildings 69 

Vaults  and  safes 69 

Behavior  of  structural  members  and  materials 71 

Behavior  of  individual  structures 76 

Academy  of  Sciences  building 76 

iEtna  (Young,  or  Commissary)  Building 76 

Appraisers’  warehouse : 77 

Aronson  Building 78 


CONTENTS. 


V 


The  Effects  of  the  Earthquake  and  Fire  on  Buildings,  etc. — Com- 
tinued. 

Earthquake-  and  fire-resisting  qualities  of  structures,  etc. — Continued. 

Behavior  of  individual  structures — Continued.  Page. 

Bullock  & Jones  Building 80 

Call  Building 81 

Chronicle  buildings 83 

City  hall  and  hall  of  records 84 

Cowell  Building 89 

Crocker  Building 89 

Crocker  Estate  Building 90 

Dewey  monument I 90 

Emporium 90 

Fairmount  Hotel 92 

James  Flood  Building 92 

Grant  Building 93 

Hall  of  Justice 93 

Kamm  Building 93 

Kohl  Building 94 

Merchants’  Exchange  building 94 

Mills  Building 95 

United  States  mint 95 

Monadnock  Building 96 

Mutual  Life  Building 96 

Pacific  States  Telephone  and  Telegraph  Building 96 

Palace  Hotel 97 

Post-office  building 97 

Rialto  Building 103 

St.  Francis  Hotel 103 

Shreve  Building 104 

Sloane  Building 104 

Spring  Valley  Water  Company’s  building 104 

Union  Ferry  Building__ 105 

Union  Trust  Company’s  building 108 

Miscellaneous  structures v 108 

General  discussion 108 

Ordinary  buildings  and  residences 110 

Chimneys 111 

Brick  smokestacks 112 

Conditions  outside  of  San  Francisco 112 

Oakland 112 

Palo  Alto 112 

Other  towns 114 

Fortifications 114 

Reservoirs,  pipe  lines,  and  other  structures  along  the  fault 

line ; 114 

General  conclusions 116 

The  rebuilding  of  San  Francisco 116 

Distribution  systems  for  waterworks 117 

Sewers 118 

Fire-resisting  features  of  buildings  in  “ congested  districts  ” 119 


VI 


CONTENTS. 


The  Effects  of  the  Earthquake  and  Fire  on  Buildings,  etc. — Con- 
tinued. 

General  conclusions — Continued.  Page. 

Fireproofing 119 

Protection  of  openings 122 

Fireproof  vaults 124 

Constructions  and  materials  recommended  for  earthquake  locali- 
ties  -a. 124 

The  minimizing  of  fire  losses 126 

Earthquake  insurance 129 

Summary 129 

The  Earthquake  and  Fire  and  their  Effects  on  Structural  Steel  and 

Steel-Frame  Buildings,  by  Frank  Soule 131 

The  earthquake 131 

Geologic  features 131 

A study  of  the  effect  of  natural  features  on  the  intensity  of 

destruction 132 

Distance  from  the  fault  line 132 

Soil  formation 133 

The  fire 136 

General  description 136 

Abstract  of  report  of  engineers’  committee  of  the  National  Board 

of  Fire  Underwriters 139 

Extracts  from  a San  Francisco  fire  expert’s  report  to  the  British 

fire-prevention  committee 140 

Effect  of  the  layout  of  the  city  and  the  character  of  the  buildings-  141 
Behavior  of  structural  steel  and  steel-frame  buildings  subjected  to  the 

earthquake  and  fire 142 

Effects  due  primarily  to  the  earthquake 142 

Introduction 142 

Foundations 143 

Structural-steel  frames  exposed  to  vibratory  motion 143 

Masonry  walls  and  stonework 145 

Reliability  of  structural  steel 145 

Effects  of  the  fire 146 

Buildings  146 

Fireproofing 147 

General  conditions 147 

Concrete 147 

Terra  cotta 148 

Plaster  and  metal  work 148 

Brickwork  149 

Reenforced  concrete  _5 . — 150 

Lessons  from  the  various  types  of  buildings 150 

Fire-fighting  apparatus  and  fire-resisting  materials 153 

Final  conclusions 157 

Earthquake  protection 157 

Fire  protection 157 

Acknowledgments 158 

List  of  Papers  Relating  to  the  Earthquake  and  Fire 159 

Index 163 


ILLUSTRATIONS. 


(All  the  plates  will  be  found  at  the  end  of  the  bulletin.) 


Plate  I.  Earthquake  effects  along  the  fault  trace : A,  Road  crossing  fault 
trace  near  Point  Reyes  station ; B,  Fence  parted  by  earthquake 
fault. 

II.  Redwood  tree  on  line  of  fault  south  of  Fort  Ross,  showing  earth- 
quake effect  along  the  fault  trace. 

III.  Fault  trace  near  Point  Reyes  station. 

IV.  A,  Secondary  cracks,  shore  of  Bolinas  Lagoon ; B,  Secondary  cracks, 

with  settling,  Bolinas. 

V.  Results  of  earth  flow,  Ninth  street,  San  Francisco. 

VI.  Earthquake  effects  on  “ made  ground A,  Settling  on  Dore  street ; 
B,  Buckling  caused  by  earth  flow,  Howard  street. 

VII.  Shifted  bottom  of  Tomales  Bay:  A,  General  view;  B,  Edge  of  new 
shoal. 

VIII.  A,  Earthquake  ridges  on  tidal  flat,  Tomales  Bay;  B,  Slipping  of 
alluvial  soil  toward  a river. 

IX.  Damage  to  Pilarcitos  30-inch  pipe  line  by  earthquake. 

X.  A,  Collapsed  30-inch  wrought-iron  pipe  near  trestle  crossing  the 
fault ; B,  House  on  line  of  fault,  torn  asunder  by  earthquake. 

XI.  A,  Racking  and  spalling  of  concrete  pier  due  to  earthquake  move- 
ment ; B,  Endurance  of  concrete  dam  near  fault  trace  at  Crystal 
Springs  Lake,  San  Mateo. 

XII.  A,  Effect  of  earthquake  on  a brick  building  near  Salinas  (Spreck- 
els’s  sugar  mill)  ; B,  Earthquake  wreck  of  Hall  of  Justice,  San 
Jose. 

XIII.  A,  Comparative  earthquake  endurance  of  dissimilar  structures  near 

San  Jose;  B,  Earthquake  effect,  high  school  building,  San  Jose. 

XIV.  A,  Comparative  behavior  of  reenforced  concrete  and  brickwork  under 

earthquake  vibration ; B,  Complete  wreck  by  earthquake  at  Santa 
Rosa. 

XV.  Endurance  of  steel  framework  as  affected  by  method  of  support, 
Leland  Stanford  Junior  University : A,  Undamaged  steel  frame- 
work supporting  dome  of  library  ; B,  Collapse  of  brick  walls  causing 
destruction  of  steel  skeleton  dome  of  gymnasium. 

XVI.  Memorial  arch,  Leland  Stanford  Junior  University : A,  Before  the 
earthquake  ; B,  Earthquake  effect. 

XVII.  A,  Collapse  due  to  lack  of  tie  between  walls  and  frame;  B,  Col- 
lapsed tower  and  general  earthquake  wreckage. 

XVIII.  A,  Earthquake  damage  due  to  lack  of  tie  and  bracing;  B,  Earth- 
quake effect  on  arches. 

XIX.  Earthquake  effects  on  cement-block  walls  : A,  Endurance  of  walls 
tied  together  with  steel  rods ; B,  Wall  thrown  down  by  earth- 
quake vibrations  of  roof  trusses  which  were  not  tied  to  wall. 


VII 


VIII 


ILLUSTRATIONS. 


Plate  XX.  A,  Loosening  of  arch  stones  and  spalling  of  columns  by  earthquake ; 
B,  Undamaged  reenforced-concrete  structure. 

XXI.  A,  Racking  of  newly  constructed  building;  B,  Good  earthquake 
endurance  of  buttressed  walls. 

XXII.  A,  X cracks  in  brickwork,  caused  by  rocking;  B,  Slip  of  founda- 
tion of  cyclorama,  causing  collapse  of  the  structure. 

XXIII.  A,  Earthquake  effect  on  structure  of  reenforced  concrete  of  poor 
quality ; B,  Effect  of  earthquake  on  adjacent  buildings  of  dis- 
similar type  and  construction. 

XXIV.  A,  Failure  of  cast-iron  shell  of  concrete-filled  cast-iron  columns  by 
fire ; B,  Spalled  granite,  Market  street  entrance  of  2Etna  Build- 
ing, San  Francisco. 

XXV.  A,  Subsidence  of  street  in  front  of  JEtna  Building;  B,  Fire  en- 
durance of  concrete. 

XXVI.  A,  Buckled  columns  and  collapsed  floor  panel ; B,  Incipient  fail- 
ure of  naked  cast-iron  column  in  city  hall. 

XXVII.  A,  Earthquake  endurance  of  reenforced-concrete  building ; B, 
Failure  of  terra-cotta  column  coverings,  resulting  in  buckled 
columns. 

XXVIII.  A , Earthquake  endurance  of  a well-constructed  brick  building ; B, 
Failure  of  ornamental  terra  cotta. 

XXIX.  A,  Earthquake  cracks  in  walls  of  vault ; B,  Collapse  of  floor  panel 
caused  by  fall  of  load  from  floor  above. 

XXX.  A,  Earthquake  damage  minimized  by  special  construction,  Dewey 
monument,  San  Francisco ; B,  X cracks  in  walls  due  to  rocking 
of  building  by  earthquake,  Chronicle  Building,  San  Francisco. 

XXXI.  Ruin  of  the  seven-million-dollar  city  hall,  San  Francisco. 

XXXII.  Complete  failure  of  slow-burning  wood  construction. 

XXXIII.  A,  Behavior  of  steel  frame;  B,  Earthquake  damage  to  stone  piers. 

XXXIV.  Buckling  of  columns  due  to  failure  of  plastered  metal-lath  fire- 
proofing. 

XXXV.  A,  Incipient  buckling  of  columns  from  heat;  B,  Failure  of  sus- 
pended ceiling. 

XXXVI.  A,  Granite  columns  spalled  by  fire;  B,  Buckling  of  columns  due 
to  failure  of  wire-mesh  and  plaster  fireproofing. 

XXXVII.  A,  Stonework  spalled  by  fire;  B,  Earthquake  damage  due  to  light 
walls  and  bad  construction. 

XXXVIII.  A,  Good  earthquake  endurance  of  a building  of  the  monumental 
type ; B,  Spalling  of  stonework  by  fire. 

XXXIX.  A,  Wrecked  tower  and  spalled  stonework ; B,  Complete  wreck  by 
earthquake,  due  to  poor  design. 

XL.  A,  Spalling  of  enameled  brick  in  light  well  and  failure  of  fire- 
proofing of  window-frame  separators ; B,  Buckling  of  basement 
column  due  to  failure  of  terra-cotta  covering  in  fire. 

XLI.  A,  Endurance  of  a well-protected  building  subjected  to  severe 
radiant  heat;  B,  Warping  of  plastered  metal-lath  covering. 

XLI I.  A,  Roof  trusses  damaged  by  heat,  through  failure  of  terra-cotta 
covering;  B,  Effect  of  settling  of  ground  subjected  to  earth- 
quake vibrations. 

XLIII.  A , Cracks  in  masonry,  pavilion  of  post-office;  B,  Effect  of  slip, 
Mission  street,  San  Francisco. 

XLIV.  A,  Cracks  in  masonry  and  settling  of  outer  terrace,  post-office  build- 
ing, San  Francisco ; B,  Effect  of  earthquake  in  loosening  stone- 
work. - 


Illustrations. 


ix 


; 

Plate  XLV.  A,  Failure  of  hollow-tile  fireproofing  ; B,  Failure  of  terra-cotta  tile 
protection  and  spalling  of  lower  webs  of  floor  tiles. 

XLVI.  A , Brickwork  thrown  down  by  earthquake  vibration ; B,  Effect 
of  severe  shaking  on  well-bonded  brickwork  filled  with  good 
mortar. 

XLVII.  Sheared  rivets,  tower  of  Union  Ferry  Building,  San  Francisco. 

XLVIII.  A,  Buckling  of  basement  column  due  to  failure  of  plastered  metal- 
lath  fireproofing;  B,  Damage  said  to  have  been  caused  by 
dynamite. 

XLIX.  A,  Failure  of  basement  column  due  to  fire;  B,  Failure  of  terra- 
cotta tiling  and  metal-frame  wire-glass  windows  by  fire. 

L.  A,  Collapse  of  building  due  to  buckling  of  columns;  B , Failure  of 
terra-cotta  tile  covering  in  fire. 

LI.  Effects  of  heat  on  steel  work. 

LII.  A,  Endurance  of  brick  vault;  B,  Absolute  failure  of  so-called  fire- 
proof safes. 

LI  1 1.  A,  Earthquake  damage  to  brick  stack ; B,  General  earthquake 
effect  on  frame  buildings. 

LIV.  Destruction  by  fire,  San  Francisco;  view  westward  from  Tele- 
graph Hill. 

LV.  Destruction  by  fire,  San  Francisco ; panorama  from  corner  of 
Pine  and  Powell  streets. 

LVI.  Map  of  San  Francisco,  showing  burned  district. 

LVII.  Map  of  San  Francisco  and  vicinity,  showing  relation  of  burned 
district  to  entire  city. 

Fig.  1.  Map  of  the  fault  trace,  page  3. 

2.  Diagrams  illustrating  the  nature  of  the  earthquake-making  fault,  page  4. 


PREFACE. 


I 


By  Joseph  A.  Holmes. 


Immediately  after  the  San  Francisco  earthquake  and  fire  of  April 
18, 1906,  it  was  decided  to  arrange  for  an  investigation  of  their  effects 
on  buildings  and  materials  of  construction.  Accordingly,  on  April 
19  Richard  L.  Humphrey  was  sent  to  San  Francisco  for  this  pur- 
pose, as  secretary  of  the  National  Advisory  Board  on  Fuels  and  Struc- 
tural Materials  and  representing  the  structural  materials  division 
of  the  United  States  Geological  Survey.  At  the  request  of  the  Presi- 
dent, Capt.  John  Stephen  Sewell,  Corps  of  Engineers,  United  States 
Army,  was  sent  to  San  Francisco  on  a similar  errand  by  the  War  De- 
partment under  order  of  April  23,  1906.  Frank  Soule,  dean  of  the 
college  of  civil  engineering  of  the  University  of  California,  w as  asked 
late  in  the  fall  of  1906  to  prepare  a report  on  the  general  earthquake 
and  fire  conditions.  G.  K.  Gilbert,  of  the  United  States  Geological 
Survey,  also  a member  of  the  California  earthquake  investigation 
commission,  who  was  near  San  Francisco  at  the  time  of  the  disaster, 
was  asked  to  prepare  a brief  special  report  on  the  phenomena  of  the 
earthquake. 

Mr.  Gilbert  has  brought  into  his  paper  only  the  salient  features 
and  results  of  the  earthquake,  for  the  reason  that  the  subject  is  being 
treated  more  fully  in  the  report  of  the  California  earthquake  inves- 
tigation commission. 

Mr.  Humphrey,  who  during  the  last  two  years  has  had  charge  of 
the  structural  materials  laboratories  of  the  United  States  Geological 
Survey,  has  had  many  years’  experience  in  the  investigation  of  struc- 
tural materials,  especially  with  regard  to  their  fire-resisting  qualities. 

Before  going  to  San  Francisco  Captain  Sewell  had  studied  care- 
fully the  effects  of  fire  on  buildings  and  materials,  especially  as  indi- 
cated by  the  results  of  the  conflagration  at  Baltimore  in  1904. 

Professor  Soule  has  had  the  advantage  not  only  of  a large  experi- 
ence, but  also  of  being  thoroughly  familiar  with  the  conditions  in 
San  Francisco  prior  to  the  earthquake  and  fire,  and  of  being  on  the 
ground  during  their  occurrence.  He  has  had  subsequently  every 
opportunity  for  studying,  at  first  hand  and  in  great  detail,  the  effects 
of  both  the  earthquake  and  the  fire. 


XI 


XII 


PREFACE. 


The  investigations  of  these  three  engineers  were  conducted  inde- 
pendently, and  their  reports  have  been  prepared  without  collabora- 
tion. Under  these  circumstances  there  are  necessarily  some  differ- 
ences of  opinion  as  to  matters  of  detail,  but  as  to  the  more  important 
features  the  writers  are  in  hearty  accord.  About  four  hundred  illus- 
trations were  submitted  with  the  original  reports;  many  of  these  do 
not  appear  with  the  printed  reports  because  their  use  would  have 
involved  duplication,  but  wherever  a view  given  by  one  author  was 
rejected  because  of  its  similarity  to  a view  by  another  author  show- 
ing the  same  engineering  features,  a reference  to  the  accepted  view 
has  been  inserted.  The  legend  appended  to  each  illustration  indi- 
cates whether  the  original  view  was  actually  taken  by  the  author  or 
was,  procured  from  another  source. 

Persons  interested  in  this  subject  are  advised  not  only  to  read  each 
of  these  papers,  but  also  to  consult  a number  of  other  important 
papers  on  this  subject  which  have  appeared  in  the  different  technical 
journals  and  the  proceedings  of  technical  societies  during  the  last 
several  months.  (See  list  at  end  of  bulletin,  pp.  159-161.) 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE  OF  APRIL 
18,  1906,  AND  THEIR  EFFECTS  ON  STRUCTURES  AND 
STRUCTURAL  MATERIALS. 


By  G.  K.  Gilbert,  R.  L.  Humphrey,  J.  S.  Sewell,  and  Frank  Soule. 


THE  EARTHQUAKE  AS  A NATURAL  PHENOMENON. 


By  G.  K.  Gilbert. 


INTRODUCTION. 

The  investigations  to  which  the  San  Francisco  earthquake  has 
given  rise  are  of  two  classes — the  study  of  the  natural  phenomena 
constituting  or  associated  with  the  earthquake,  and  the  study  of  the 
relations  of  the  San  Francisco  earthquake  and  future  earthquakes  to 
human  activities. 

The  principal  studies  of  the  earthquake  as  a natural  phenomenon 
are  under  the  direction  of  the  California  earthquake  investigation 
commission,  which  was  appointed  by  the  governor  of  the  State 
three  days  after  the  occurrence  of  the  shock.  The  human  or  economic 
aspects  of  the  subject  have  been  studied  chiefly  by  engineers  and 
architects,  of  whom  a number  have  acted  in  private  capacity,  while 
others  have  acted  as  the  representatives  of  governmental  or  private 
organizations.  In  many  of  the  architectural  studies  the  earthquake 
and  fire  have  been  considered  together,  as  the  destructive  effects  of 
these  two  sources  of  danger  were  closely  associated  in  the  San 
Francisco  disaster. 

This  volume  is  devoted  to  certain  economic  aspects  of  the  subject, 
and  the  present  chapter  on  natural  phenomena  of  the  earthquake 
selects  those  features  which  seem  contributory  to  an  understanding 
of  the  papers  which  follow.  A fuller  account  of  the  earthquake 
may  be  found  in  the  preliminary  report  of  the  State  commission 

1 


2 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


above  referred  to ; and  a monographic  report  is  to  be  expected  when 
the  labors  of  this  commission  shall  have  been  completed.® 

An  earthquake  is  a jar  occasioned  by  some  violent  rupture.  Some- 
times the  rupture  results  from  an  explosion,  but  more  commonly 
from  the  sudden  breaking  of  rock  under  strain.  The  strain  may  be 
caused  by  the  rising  of  lava  in  a volcano  or  by  the  forces  that  make 
mountain  ranges  and  continents.  The  San  Francisco  earthquake  of 
April  18,  1906,  had  its  origin  in  a rupture  associated  with  mountain- 
making forces.  A rupture  of  this  sort  may  be  a mere  pulling  apart 
of  the  rocks  so  as  to  make  a crack,  but  examples  of  that  simple  type 
are  comparatively  rare.  The  great  majority  of  ruptures  include  not 
only  the  making  of  a crack  but  the  relative  movement  or  sliding  of 
the  rock  masses  on  the  two  sides  of  the  crack ; that  is  to  say,  instead 
of  a mere  fracture  there  is  a geologic  fault.  After  a fault  has  been 
made  its  walls  slowly  become  cemented  or  welded  together;  but  for 
a long  time  it  remains  a plane  of  weakness,  so  that  subsequent  strains 
are  apt  to  be  relieved  by  renewed  slipping  on  the  same  plane  of 
rupture,  and  hundreds  of  earthquakes  may  thus  originate  in  the 
same  place. 

A faulting  may  occur  far  beneath  the  surface  and  be  known  only 
through  the  resulting  earthquake;  but  some  of  the  quake-causing 
ruptures  extend  to  the  surface,  and  thus  become  visible.  The  New 
Madrid  and  Charleston  earthquakes  are  examples  of  those  having 
deep-seated  origins;  the  shocks  at  Inyo  and  San  Francisco,  of  those 
whose  causative  faults  reached  the  surface  of  the  ground. 

The  San  Francisco  earthquake  had  its  origin,  wholly  or  chiefly,  in 
a new  slipping  on  the  plane  of  an  old  fault.  The  trend  of  the  fault 
is  northwest  and  southeast,  and  it  is  known  through  a distance  of  sev- 
eral hundred  miles.  Visible  evidence  of  fresh  slipping — a surface 
trace,  to  be  described  presently — does  not  appear  through  its  whole 
extent,  but  has  been  traced  from  San  Juan  at  the  south  to  Point 
Arena  at  the  north  (fig.  1),  a distance  of  about  180  miles.  Because 
the  earthquake  was  severe  in  Priest  Valley,  60  miles  southeast  of  San 
Juan,  it  is  thought  that  subterranean  slipping  on  the  old  fault  plane 
extended  beyond  San  Juan.  At  Point  Arena  the  visible  fault  trace 
passes  under  the  ocean,  and  the  line  of  its  trend  does  not  again  touch 
the  coast,  so  that  its  northwestern  course  and  extent  are  in  doubt. 
A fault  trace  which  appears  at  Point  Delgada,  75  miles  to  the  north, 
may  be  part  of  its  continuation  or  may  represent  a separate  fracture. 
In  a general  way  the  intensity  of  the  shock  was  greatest  near  the 

a The  California  earthquake  investigation  commission  is  composed  of  Andrew  C. 
Lawson  (chairman),  A.  0.  Leuschner  (secretary),  G.  K.  Gilbert,  H.  F.  Reid,  J.  C.  Branner, 
George  Davidson,  Charles  Burkhalter,  and  W.  W.  Campbell.  Its  work  is  organized  under 
three  committees — a committee  on  isoseismals,  A.  C.  Lawson,  chairman  ; a committee  on 
coseismals,  A.  O.  Leuschner,  chairman,  and  a committee  on  the  geophysics  of  the  earth- 
quake, H.  F.  Reid,  chairman. 


THE  EARTHQUAKE  AS  A NATURAL  PHENOMENON. 


3 


fault  trace  and  diminished  with  distance  therefrom;  but  to  this  rule 
there  are  important  exceptions,  and  it  has  been  noted  especially 


Fig.  1. — Map  of  the  fault  trace.  Broken  lines  indicate  alternative  hypotheses  as  to  its 
extension  north  of  Point  Arena. 

that  an  area  of  high  intensity  coincided  approximately  with  the 
Santa  Rosa  Valley,  which  trends  northwestward,  parallel  to  the  main 


4 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


fault.  As  the  ridges  of  the  neighboring  Coast  Range  have  the  same 
northwesterly  trend,  it  is  thought  probable  that  a subterranean  slip- 
ping here  occurred  on  a fault  associated  with  the  valley.  In  that 
case  the  geologic  event  causing  the  earthquake  included  coincident 
or  nearly  coincident  yielding  on  more  than  one  fault  plane  of  the 
Coast  Range  system,  and  various  other  peculiarities  in  the  distribu- 
tion of  intensity  may  be  ascribed  to  local  faulting. 

The  region  of  high  intensity,  to  which  most  of  the  destruction  was 
limited,  is  a belt  20  to  40  miles  wide,  extending  from  the  mouth  of 
Eel  River  at  the  northwest  to  Priest  Valley  at  the  southeast  (fig.  1). 
This  belt  includes  the  surface  expression  of  the  principal  fault — a 
feature  distinctively  known  as  the  fault  trace — a large  number  of 
cracks,  and  many  local  and  superficial  dislocations  of  soil  and  rock 
variously  characterized  as  landslides  and  slumps. 

THE  FAULT  TRACE. 

The  plane  of  the  earthquake-causing  fault,  where  it  appears  at  the 
surface,  is  approximately  vertical.  The  movement  which  took  place 
along  this  plane  was  approximately  horizontal. 


As  the  statement  of  these  relations  is  sometimes  found  confusing, 
they  are  here  illustrated  diagrammatically.  The  upper  diagram  in 
fig.  2 represents  a rectangular  block  as  if  cut  from  the  land,  the  thick- 
ness being  25  feet,  the  length  east  and  west  (right  to  left)  150  feet, 
and  the  width  100  feet.  The  dotted  line  NS  indicates  the  surface 
outcrop  of  the  old  fault  plane,  trending  northwest  and  southeast, 
this  plane  cutting  the  face  of  the  block  in  the  vertical  line  SD.  AB 
stands  for  any  straight  line  on  the  surface  of  the  land — such  as  would 
be  defined  by  a road,  a fence,  or  a row  of  trees — crossing  the  fault 
outcrop  at  right  angles.  The  lower  diagram  represents  the  same 


THE  EARTHQUAKE  AS  A NATURAL  PHENOMENON. 


5 


rectangular  block  after  the  earthquake,  its  two  parts  dislocated  by 
sliding  horizontally  along  the  fault  plane,  and  the  line  AB  made  dis- 
continuous by  an  offset. 

To  return,  now,  from  the  ideal  to  the  actual,  the  sides  and  bottom 
of  the  earth  block  disappear.  The  depth  to  which  the  fault  pene- 
trates is  indefinite  and  unknown,  and  so  is  the  extent  of  the  lands  on 
either  side  affected  by  the  displacement.  For  nearly  200  miles  there 
is  a fracture  on  the  face  of  the  land,  and  everything  traversed  by  the 
fracture  is  dislocated,  the  part  on  the  southwest  side  having  appar- 
ently moved  toward  the  northwest  and  the  part  on  the  northeast  side 
having  apparently  moved  toward  the  southeast.  The  total  horizontal 
offset  ranges  in  general  from  2 to  16  feet,  but  at  one  place,  ^affected  by 
abnormal  conditions,  reaches  20  feet  (PI.  I,  A).  The  effect  is  also 
shown  by  a redwood  tree  (PI.  II),  which  was  situated  at  a place 
where  the  displacement  was  slight.  The  average  offset  is  10  to  12 
feet.  Associated  with  the  horizontal  dislocation  are  vertical  disloca- 
tions of  minor  and  variable  amount.  This  line  of  fracture,  with  the 
associated  dislocation,  is  the  surface  expression  of  the  fault  which 
occurred  on  April  18,  1906.  It  is  the  visible  trace  of  the  fault  across 
the  surface  of  the  land,  and  in  the  following  pages  will  be  called  the 
“ fault  trace.” 

The  fault  trace  itself  is  in  some  places  inconspicuous,  as  in  the  flat 
meadow  represented  in  PI.  I,  B , where  one  might  readily  walk  across 
it  without  noticing  that  the  ground  had  been  disturbed.  Its  ordinary 
phase,  however,  includes  a disruption  of  the  ground  suggestive  of  a 
huge  furrow,  consisting  of  a zone,  between  rough  walls  of  earth,  in 
which  the  ground  is  splintered  and  the  fragments  are  dislocated  and 
twisted.  This  phase  is  shown  in  PI.  III.  In  many  places  the  fault 
trace  sends  branching  cracks  into  bordering  land,  and  locally  its 
effect  in  dislocation  is  divided  among  parallel  branches. 

The  views  of  the  fault  trace  given  in  PI.  VII  represent  it  at  a 
point  not  far  from  the  head  of  Tomales  Bay,  where  it  traverses  a 
hillside  having  a general  slope  toward  the  southwest.  In  the  upper 
view  we  look  toward  the  northwest;  in  the  lower,  toward  the  south- 
southeast.  The  horizontal  displacement  is  here  about  16  feet,  the 
ground  at  the  left,  in  each  view,  having  moved  from  us,  and  the 

® In  the  case  of  an  earthquake  fault  with  important  vertical  displacement  the  surface 
expression  is  a small  cliff  or  scarp,  and  to  such  a feature  the  name  “ fault  scarp  ” has 
been  given  ; but  this  name  does  not  serve  to  characterize  the  feature  produced  by  the 
horizontal  displacement  of  April  18,  1906.  In  default  of  an  appropriate  and  established 
name  the  geologists  who  first  traced  the  feature  made  tentative  use  of  “ furrow  ” and 
“ rift ; ” and  the  word  rift  was  employed  in  the  preliminary  report  of  the  California  com- 
mission, in  a popular  article  by  the  present  writer,  and  probably  in  other  places.-  The  com- 
mission, however,  in  giving  more  deliberate  attention  to  terminology,  has  determined  to 
reserve  the  word  rift  for  a meaning  more  in  consonance  with  earlier  geologic  usage  and 
to  substitute  “ fault  trace  ” for  the  surface  expression  of  the  fault.  The  present  paper 
conforms  to  the  nomenclature  accepted  by  the  commission. 

7171— Bull.  324—07 2 


6 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


ground  at  the  right  toward  us.  There  is  also  a vertical  displacement, 
the  ground  on  the  southwest  side  having  been  relatively  lifted  1 or  2 
feet,  and  the  expression  of  the  vertical  change  is  exaggerated  in  the 
lower  view  by  the  relation  of  the  horizontal  change  to  the  local 
slope  of  the  hillside.  There  is  nothing  in  the  pictures  to  show  the 
amount  or  even  the  direction  of  the  horizontal  displacement,  but 
measurements  were  made  at  neighboring  points  where  the  fault 
trace  intersects  a road,  a trail,  and  a small  gully.  The  nature  of  the 
evidence  as  to  displacement  is  illustrated  by  PI.  I,  B , which  shows  a 
dislocated  fence.  The  locality  is  on  the  farm  of  E.  R.  Strain, 
near  the  head  of  Bolinas  Lagoon,  and  the  camera  was  directed 
toward  the  northeast — at  right  angles  to  the  trend  of  the  fault  trace. 
The  main  branch  of  the  fault  trace  (which  is  here  divided)  crosses 
the  foreground  from  left  to  right,  touching  the  dissevered  ends  of  the 
fence,  but  the  shear  is  at  this  point  so  smooth  that  its  surface  trace 
is  concealed  by  the  grass.  The  fence,  which  before  the  earthquake 
was  straight  and  continuous,  was  broken  across  and  offset  to  the  dis- 
tance of  8J  feet. 

Between  Point  Arena  and  Fort  Ross  the  course  of  the  fault  trace 
(see  fig.  1,  p.  3)  is  approximately  parallel  to  the  coast,  passing  to  the 
east  of  all  the  coastal  towns.  From  Fort  Ross  to  the  head  of  Tomales 
Bay  it  traverses  the  water,  except  at  Bodega  Bay  and  Preston  Point, 
where  for  short  distances  it  crosses  the  land.  It  again  enters  the 
water  at  Bolinas  Lagoon,  passing  several  miles  outside  the  Golden 
Gate,  and  returning  to  the  land  at  Mussel  Rock,  whence  it  follows  a 
nearly  direct  course  to  San  Juan.  It  does  not  touch  any  large  town, 
but  passes  within  a mile  of  Manchester,  Plantation  post-office,  Fort 
Ross,  Bodega,  Inverness,  Point  Reyes  station,  Olema,  Woodville,  Boli- 
nas, Woodside,  Portola,  Wrights,  Chittenden,  and  San  Juan. 

On  the  east  and  west  sides  of  the  fault  trace,  respectively,  the 
right-line  distances  to  various  places  are  as  follows : 


Distances  from  the  fault  trace  to  near-by  prominent  points. 


EAST  SIDE. 


Ukiah 

Cloverdale 

Healdsburg 

Santa  Rosa 

Freestone 

San  Rafael 

Sonoma 

Petaluma 

Martinez  

Berkeley 

Oakland 

San  Francisco — city  hall 


east  side — continued. 

Miles.  Miles. 

_ 2G  San  Francisco — Cliff  House 3 

22  San  Mateo 4 

_ 20  Stanford  University 5 

_ 19  San  Jose 13 

8 

q WEST  SIDE. 

Point  Reyes  light  house 11 

- Halfmoon  Bay 6 

29  Pescadero 10 

19  Santa  Cruz 12 

- 17  Salinas 13 

_ 9 


THE  EARTHQUAKE  AS  A NATURAL  PHENOMENON. 


7 


CRACKS. 

All  through  the  area  of  high  intensity  cracks  were  made,  and  these 
were  specially  numerous  near  the  fault  trace.  The  cracks  were 
also  more  numerous  in  soft  alluvium  than  in  hard  ground,  but  the 
number  which  deeply  penetrated  the  bed  rock  was  large.  Perhaps 
this  feature  is  better  expressed  by  saying  that  the  bed  rock  was  gen- 
erally and  profoundly  shattered,  but  without  important  dislocation 
except  on  the  old  fault  plane.  The  wide  prevalence  of  shattering  is 
shown  by  the  derangement  of  the  underground  circulation  of  water. 
In  every  farming  district  within  the  main  earthquake  belt  persons 
familiar  with  the  springs  noted  changes  in  the  flow  of  water,  rang- 
ing from  moderate  diminution  or  increase  to  complete  stoppage  or 
to  the  breaking  out  of  new  springs.  In  some  places  the  derange- 
ments were  temporary  only,  but  more  commonly  a permanent  change 
was  reported. 

At  the  surface  the  cracks  had  great  variety  of  expression.  Some 
were  barely  perceptible  as  partings ; others  gaped  so  widely  that  one 
might  look  down  them  several  yards.  Some  were  mere  pullings 
apart;  others  showed  small  differential  movements  of  the  nature  of 
faulting.  Some  were  solitary;  others,  especially  those  exhibiting 
faulting,  were  in  groups.  Some  straggled  and  branched  irregularly ; 
others  were  nearly  straight  for  hundreds  of  feet.  Theoretically,  some 
cracks  were  primary  as  regards  the  earthquake  and  others  secondary ; 
that  is  to  say,  some  were  caused  directly  by  the  preexistent  stresses 
which  produced  the  main  fault  and  others  were  caused  by  the  waves 
constituting  the  earthquake. 

PI.  IV  shows  two  types  of  secondary  cracks.  In  A the  cracks  are 
crooked  and  without  faulting.  They  traverse  tidal  mud  near  the 
head  of  Bolinas  Lagoon  and  are  near  the  main  branch  of  the  fault 
trace,  which  follows  the  base  of  the  bluff  seen  at  the  right.  The 
cracks  seen  in  B are  in  Bolinas,  within  half  a mile  of  the  supposed 
position  of  the  fault  trace.  The  greater  part  of  the  village  lies  in  a 
narrow  valley  dividing  a plateau.  The  valley  floor  is  of  alluvium, 
the  surface  of  which  curves  upward  at  the  sides.  As  a result  of  the 
earthquake  the  alluvium  settled  somewhat  toward  the  middle  of  the 
valley,  thus  forming  along  the  bases  of  the  hills  a system  of  cracks 
associated  with  faulting. 

DISLOCATIONS  OF  SURFACE  MATERIAL. 

The  district  most  strongly  affected  by  the  earthquake  is  one  in 
which  landslips  are  normally  of  frequent  occurrence.  On  many  hill 
slopes  were  masses  of  earth  or  rock,  the  descent  of  which  was  sure  to 
take  place  whenever  conditions  became  favorable.  The  shaking  of 


8 


THE  SAN  FEANCISCO  EAETHQTJAKE  AND  FIKE. 


the  earth  on  the  morning  of  April  18,  1906,  supplied  the  lacking 
factor,  and  they  were  all  loosened  at  once.  In  the  simplest  case,  a 
poised  rock  toppled  over  and  rolled  down  a slope.  In  other  cases 
adhesion  was  overcome,  with  resultant  sliding.  In  yet  others  strains 
occasioned  by  the  sapping  of  cliffs  were  reinforced  by  kinetic  strains 
and  cohesion  was  overcome,  with  resultant  fracture.  Elsewhere  an 
unconsolidated  formation,  even  though  in  a dry  condition,  was  made 
to  flow  by  simple  agitation.  Hillside  bogs  and  other  bodies  of  wet 
earth  lost  coherence  and  flowed  as  mud.  Slips  of  this  character  grade 
into  those  of  wet  alluvium  or  “ made  ground  ” resting  upon  gentle 
slopes — ground  which  under  ordinary  conditions  flows  or  creeps  at  an 
almost  imperceptible  rate,  but  which  by  shaking  was  made  to  move 
several  feet  or  yards  in  a few  seconds.  The  filled  districts  of  San 
Francisco  afford  several  examples,  and  two  of  these  are  illustrated  by 
Pis.  V and  VI,  B.  The  view  shown  in  PI.  Y is  northwestward  on 
Ninth  street,  near  Brannan.  Before  the  earthquake  the  car  tracks 
and  curb  line  were  straight  and  approximately  level,  and  this  condi- 
tion was  not  disturbed  on  the  relatively  firm  ground  shown  in  the 
distance.  In  the  nearer  part  of  the  view  the  street  crosses  a tract  of 
made  ground  created  by  filling  a valley  tributary  to  a narrow  tidal 
inlet  called  Mission  Creek.  The  descent  of  this  valley  was  south- 
westward,  and  the  made  ground  flowed  in  that  direction,  carrying 
street  and  buildings  with  it.  In  taking  the  photograph  reproduced 
in  PI.  VI,  B , the  camera  stood  on  ground  made  by  the  filling  of  Mis- 
sion Lagoon,  an  expansion  of  Mission  Creek,  and  was  pointed  north- 
ward, commanding  a portion  of  Howard  street.  The  made  ground 
here  flowed  northeastward  and  the  buckling  of  street-car  tracks  was 
caused  by  its  motion.  Where  the  same  earth  flow  crossed  Valencia 
street  the  horizontal  movement  amounted  to  6 feet. 

In  the  various  cases  of  dislocation  enumerated  the  motive  force 
appeared  to  be  gravity,  and  the  apparent  function  of  the  earthquake 
was  to  initiate  movement  by  overcoming  equilibrium,  adhesion,  or 
cohesion,  or  else  to  increase  mobility  by  agitation,  and  thereby  tem- 
porarily convert  a quasi  solid  into  a quasi  liquid.  While  I do  not 
doubt  that  this  explanation  is  ordinarily  adequate,  there  is  at  least 
one  dislocation  of  surface  material  for  which  it  is  inadequate,  and 
this  raises  the  question  whether  in  various  other  instances  it  may 
not  require  qualification.  I refer  to  an  extensive  shifting  of  mud  on 
the  bottom  of  Tomales  Bay.  At  the  head  of  the  bay  and  thence  for 
a distance  of  several  miles  northwestward  the  soft  mud  was  moved 
bodily  westward.  It  not  only  descended  from  the  northeast  shore,  so 
as  to  cause  deeper  Water,  but  ascended  toward  the  southwest  shore, 
creating  a broad  shoal  (PI.  VII).  The  horizontal  change  of  posi- 
tion near  the  southwest  shore  was  in  places  more  than  25  feet,  and 


THE  EARTHQUAKE  AS  A NATURAL  PHENOMENON. 


9 


the  vertical  change  as  much  as  2 feet.  As  the  ascending  movement 
can  not  be  ascribed  to  gravity,  it  must  be  referred  to  the  earthquake, 
even  though  the  way  in  which  the  earth  waves  produced  the  effect  is 
not  evident.  The  locality  is  adjacent  to  the  fault  trace,  the  position 
of  which  is  along  the  bottom  of  the  bay,  east  of  the  shoal. 

The  illustrations  may  require  a few  words  of  explanation.  The 
upper  view  of  PI.  VII  looks  northward  from  the  southwest  shore 
of  the  bay.  Tide  being  low,  the  newly  formed  shoal  or  mud  bank  is 
broadly  exposed,  but  the  receding  tide  has  left  a lane  of  water  to 
mark  the  separation  of  the  mud  bank  from  the  firmer  ground  that 
withstood  the  quaking.  Immediately  after  the  earthquake  the  mud 
was  rigid,  as  in  the  tract  shown  in  PL  VIII,  A;  but  before  the  view 
of  PI.  VII,  A , was  taken  (April  28, 1906)  the  surface  had  been  largely 
smoothed  by  the  action  of  wind  waves.  A single  ridge  which  es- 
caped that  action  appears  at  the  left  in  the,  upper  view  of  PL  VII 
and  in  the  foreground  of  the  lower  view. 

A permanent  disturbance  of  the  ground  also  resulted  in  many 
instances  from  compacting.  Just  as  sand  or  grain  that  has  been 
jooured  into  a measure  can  be  made  by  shaking  to  settle  down  and 
occupy  less  space,  so  various  loose  formations,  and  especially  arti- 
ficial fillings,  were  shaken  together  by  the  earthquake  and  the  ground 
surface  lowered.  In  such  compacting  the  particles  making  up  the 
aggregate  are  readjusted  so  as  to  fit  more  closely  together  and  the 
voids  are  reduced.  In  dry  formations  compacted  by  the  earthquake 
the  reduction  of  voids  was  opposed  only  by  the  elasticity  of  the 
contained  air.  In  wet  formations  it  encountered  the  effectual  resist- 
ance of  the  contained  water,  and  could  be  accomplished  only  by  the 
extravasation  of  some  of  the  water.  Ordinarily  it  was  impossible  to 
measure  the  settling  due  to  compacting,  or  even  to  determine  its 
occurrence  as  a phenomenon  independent  of  ground  flow,  but  it  was 
clearly  seen  in  various  localities  in  San  Francisco  where  those  parts 
of  graded  streets  which  retained  their  simple  shapes  and  straight 
lines  served  as  reference  planes  for  neighboring  parts  that  were 
disturbed.  (Compare  the  distance  and  foreground  of  PL  V. 
Another  example  of  the  effect  on  the  filled-in  land  in  this  part  of 
the  city  is  shown  in  Pl.  VI,  A , a view  of  Dore  street  between  Bryant 
and  Brannan  streets.  The  settling  of  the  soft  ground  caused  the 
street  to  drop  at  least  5 feet  at  this  place.) 

The  only  notable  water  waves  generated  by  the  shock  were  in 
Tomales  Bay,  where  a group  of  waves  estimated  to  be  6 or  8 feet  high 
came  to  the  northeast  shore.  The  automatic  tide  v a^e  at  the  Presidio 
showed  a depression  of  about  4 inches,  with  subsequent  oscillations 
of  similar  amount.  Water  was  spilled  from  tanks,  etc.,  and  in  at 
least  one  place  was  thrown  from  a pool  out  on  the  land. 


10  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

MOTIONS  CONSTITUTING  TIIE  EARTHQUAKE. 

The  earthquake  occurred  between  10  and  15  minutes  after  5 o'clock 
a.  m.,  standard  time  of  the  one  hundred  and  twentieth  meridian.  As 
time  was  consumed  in  the  propagation  of  the  shocks,  the  moment  of 
beginning  at  any  place  depended  in  part  on  the  distance  of  the  place 
from  the  zone  in  which  the  disturbance  originated.  As  this  zone  was 
hundreds  of  miles  in  extent  it  is  probable  that  the  time  of  beginning 
was  not  the  same  at  all  points  along  it.  For  similar  reasons  the  char- 
acter and  sequence  of  the  motions  constituting  the  earthquake  were 
not  the  same  at  any  two  localities,  and  the  differences  in  the  vicinity 
of  the  zone  of  origin  may  have  been  very  great.  In  and  near  San 
Francisco  the  principal  part  had  a duration  of  about  one  minute;  it 
was  preceded  by  comparatively  faint  tremors  for  several  seconds,  and 
it  was  followed  by  minor  tremors.  During  the  stronger  part  the 
motion  was  chiefly  in  horizontal  directions  and  oscillatory,  but  its 
rhythm  was  irregular  in  period  and  emphasis.  On  firm  ground  in  the 
same  region  the  range  of  motion  is  believed  to  have  been  more  than  2 
inches,  but  was  not  measured,  there  being  no  seismograph  capable  of 
recording  it.  On  soft  ground  the  range  of  oscillatory  motion  may 
have  been  several  times  greater,  and  it  was  also  greater  in  the 
immediate  vicinity  of  the  fault  trace. 

The  following  paragraphs  present  my  conception  of  the  essential 
character  of  the  motions  constituting  the  earthquake  in  the  region 
of  its  destructive  intensity.  In  the  endeavor  to  make  a brief  and 
clear  statement  the  conception  is  expressed  somewhat  badly,  with 
little  reference  to  the  various  uncertainties  of  fact  and  theory  by 
which  it  is  actually  qualified. 

The  earthquake  fault  has  a length  of  300  miles,  possibly  400. 
Nothing  is  known  of  its  depth.  It  coincides  with  a plane;  of  earlier 
faulting,  on  portions  of  which  there  have  been  movements  within  a 
few  decades.  The  fact  of  recurrence  on  the  same  plane  shows  that 
the  rock  faces  in  contact  had  not  become  welded,  so  that  the  molec- 
ular force  which  there  resisted  motion  was  less  than  the  cohesion 
of  solid  rock  and  may  have  been  little  stronger  than  adhesion.  A 
tract  of  the  crust  including  the  fault  plane  had  come  to  be  affected 
by  a system  of  slowly  increasing  shearing  strains,  and  the  associated 
stresses  were  the  forces  directly  causing  the  fault.  When  the  stress 
component  coincident  with  the  fault  plane  at  some  point  became 
greater  than  the  adhesion  (or  cohesion)  a local  slipping  took  place. 
This  caused  a redistribution  of  strains  and  stresses,  the  local  relief 
of  strain  being  followed  by  increase  of  strain  and  stress  in  all  adjoin- 
ing tracts  of  the  fault  plane,  with  the  result  that  the  adhesion  was 
overcome  in  those  tracts  and  the  area  of  incipient  faulting  thereby 
enlarged.  Thus  from  the  initial  tract  the  lesion  was  propagated 
as  a sort  of  wave  through  all  the  fault  plane. 


THE  EARTHQUAKE  AS  A NATURAL  PHENOMENON. 


11 


At  the  initial  tract  a small  movement  sufficed  to  relieve  the  local 
strain,  and  the  motion  was  then  arrested  by  friction,  but  the  move- 
ment was  renewed  by  reaction  from  other  tracts,  and  it  alternately 
started  and  stopped  till  the  accumulated  stresses  had  spent  them- 
selves. There  was  a similar  rhythmic  sequence  in  other  parts  of  the 
fault,  the  frequency  of  the  alternations  depending  on  local  conditions ; 
and  the  total  movement  of  dislocation  at  each  point  was  accomplished 
by  a series  of  steps  and  not  by  a single  leap. 

The  time  consumed  in  these  reactions  was  not  infinitesimal.  The 
rate  of  propagation  of  changes  in  strain  was  of  the  same  order  of 
magnitude  as  that  of  earthquake  waves  in  general,  and  the  rate  of 
propagation  of  the  initiation  of  movement  on  the  old  fault  plane 
may  have  been  somewhat  slower  because  of  the  necessity  of  accumu- 
lating a certain  amount  of  stress  increment  to  overcome  the  adhesion. 
It  is  probable  that  the  completion  of  the  fault  required  more  than 
one  minute,  and  it  may  have  required  more  than  two  minutes.  It  is 
even  possible  that  the  displacement  had  been  completed  at  the  ini- 
tial point  before  it  began  at  the  most  remote. 

In  the  succession  of  slippings  and  stoppings  at  any  point  of  the 
fault  plane  each  separate  slip  communicated  a jar  or  pulse  to  the 
surrounding  rock,  and  this  pulse  was  propagated  in  all  directions. 
The  earthquake  at  any  locality  in  the  neighborhood  of  the  fault 
consisted  of  such  pulses  from  different  directions.  The  general  dis- 
tribution of  intensity  indicates  that  the  pulses  weakened  in  trans- 
mission somewhat  rapidly,  whence  it  may  be  inferred  that  the  particu- 
lar pulses  constituting  the  dominant  elements  of  the  local  earthquake 
were  those  from  the  nearer  parts  of  the  fault. 

If  this  conception  of  the  earthquake  is  correct,  the  rhythm  observed 
in  the  region  of  high  intensity  was  a phenomenon  distinct  from  the 
rhythm  of  harmonic  waves.  It  was  essentially  a frictional  rhythm, 
dependent  on  the  relation  of  certain  rock  strains  and  rock  stresses  to 
the  resistances  afforded  by  adhesion  and  sliding  friction.  It  was 
irregular  not  only  because  the  intervals  of  local  starting  and  stopping 
were  unequal,  but  because  it  was  derived  from  a considerable  area  of 
the  fault  surface,  in  which  the  local  rhythms  were  neither  harmoni- 
ous nor  synchronous. 

The  compounding  of  unevenly  spaced  pulses  from  different  points 
of  the  fault  plane  caused  both  reinforcement  and  interference,  intro- 
ducing a character  analogous  to  beats  in  music,  but  without  the  regu- 
larity of  musical  beats.  It  also  at  times  made  oscillatory  motions 
swifter  in  one  direction  than  the  other,  so  that  reciprocative  accelera- 
tions were  not  always  symmetrically  arranged.  In  less  technical 
language,  the  motion  was  jerky  and  included  abrupt  phases  that  were 
almost  blows.  The  compounding  also  introduced  variety  in  the 
direction  of  motion,  especially  at  the  end,  when  for  a short  time  the 


12 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  EIRE. 


pulses  from  remoter  parts  of  the  zone  of  origin  ceased  to  be  over- 
powered by  those  from  the  nearest  parts.  The  motion  in  that  closing 
phase  of  the  violent  part  of  the  earthquake  has  been  compared  by  an 
observer  to  the  motion  of  a vessel  in  a choppy  sea;  and  I conceive 
that  this  comparison  is  the  expression  of  a veritable  analogy. 

DISTRIBUTION  OF  INTENSITY. 

When  the  isoseismal  curves  for  this  earthquake  are  drawn  those 
for  the  higher  intensities  will  show  a remarkable  elongation  in  the 
northwest-southeast  direction.  They  will  also  show  irregularties 
expressive  of  high  intensity  in  the  Santa  Rosa  Valley  and  other 
outlying  areas.  These  features  are  related  to  the  position  and  form 
of  the  zone  or  zones  of  origin.  If  drawn  in  detail  they  will  show 
also  the  great  influence  of  peculiarities  of  geologic  formations.  De- 
tailed surveying  has  been  attempted  by  the  State  commission  only  in 
San  Francisco,  partly  because  the  results  will  there  have  the  greatest 
practical  value,  and  partly  because  the  data  are  there  most  available. 
Notwithstanding  the  abundance  of  cracks,  landslides,  and  broken 
trees  in  the  region  of  high  intensity,  it  is  nevertheless  true  that 
natural  structures  in  general  are  much  less  sensitive  to  earthquake 
violence  than  artificial  structures,  and  for  that  reason  grades  of  in- 
tensity are  most  easily  mapped  in  cities. 

The  word  “intensity”  has  various  meanings  as  applied  to  earth- 
quakes. As  technically  defined,  it  is  the  acceleration  of  the  earth 
particle  and  is  a quantity  to  be  measured  by  the  seismograph.  But 
the  field  of  instrumental  observation  is  so  limited  that  another  defini- 
tion practically  obtains — that  of  power  to  destroy,  a property  which 
depends  on  the  duration  and  direction  of  the  motion  as  well  as  its 
acceleration,  and  which  may  have  other  factors. 

It  has  long  been  known  that  buildings  and  other  structures  on 
ground  of  certain  kinds  are  more  susceptible  to  earthquake  injury 
than  on  ground  of  other  kinds,  and  these  differences  were  strikingly 
illustrated  in  San  Francisco.  The  general  fact  appears  to  be  that 
the  amplitude  of  vibration  and  the  acceleration  are  greater  in  loose, 
unconsolidated  formations  than  in  solid  rock.  The  firmer  and  more 
elastic  a rock  formation,  the  less  the  intensity  of  the  earthquake 
shocks  it  transmits  to  buildings  standing  on  it ; and  there  is  a grada- 
tion in  this  quality  from  the  firmest  bed  rock  to  the  loosest  gravel, 
sand,  and  mud.  For  strong  shocks,  at  least,  the  intensity  is  greater 
in  loose  formations  saturated  with  water  than  in  those  that  are  dry. 

Closely  related  to  the  control  of  intensity  by  the  peculiarities  of 
formations  is  the  subject  of  surface  undulations.  Observers  of  strong 
earthquakes  sometimes  report  visible  progressive  undulations  of  the 
ground,  similar  to  water  waves,  and  such  observations  are  usually 


THE  EARTHQUAKE  AS  A KATURAL  PHENOMENON.  13 

made  where  the  formations  are  alluvial.  Doubtless  many  of  the 
observations  are  fallacious,  depending  on  a subjective  illusion  as  to 
the  direction  of  verticality,  which  arises  from  the  horizontal  move- 
ments of  the  observer’s  support;  but  some  of  them  may  also  be 
objective.  Not  only  is  there  a gradation  in  physical  condition  from 
dry  earth  through  mud  to  water,  but  the  shaking  of  a loose  formation, 
whether  wet  or  dry,  overcomes  the  adhesion  of  particles  and  thereby 
imparts  for  the  time  being  a mobility  analogous  to  that  of  liquids. 
It  is  therefore  conceivable  that  gravity  waves,  altogether  analogous  to 
those  of  water,  may  be  produced  by  a violent  earthquake  on  the  sur- 
face of  a loose  formation.  Certain  ridges  on  soft  ground  caused  by 
earthquakes  in  Japan  are  inferred  by  Omori  and  Ivikuchi  to  repre- 
sent such  soil  waves  and  to  indicate  a wave  length  (crest  to  crest)  of 
20  to  40  meters.  The  San  Francisco  earthquake  produced  a similar 
ridging  on  tidal  mud  in  Tomales  Bay,  the  average  ridge  interval 
being  not  more  than  half  that  of  the  Japanese  examples.  The 
Tomales  Bay  ridges  are  roughly  parallel  to  the  fault  trace  (which  is 
close  at  hand),  have  about  the  same  irregularity  as  wind  waves,  and 
originally  ranged  in  height  from  1 to  3 feet.  They  were  observed 
chiefly,  but  not  exclusively,  on  the  body  of  mud  already  mentioned  as 
having  been  shifted  toward  the  southwest  shore.  The  tract  shown  in 
PL  VII  lies  so  low  as  to  be  submerged  much  of  the  time,  and  the 
ridges  had  been  so  nearly  obliterated  when  the  views  were  taken  that 
little  remained  besides  an  obscure  indication  of  their  ground  plan; 
but  an  area  nearer  the  head  of  the  bay,  and  probably  lying  somewhat 
higher,  not  only  seemed  to  have  preserved  its  character  when  photo- 
graphed (April  28;  see  PI.  VIII,  A ),  but  showed  little  change  when 
visited  nine  months  later. 

Notwithstanding  the  persistence  of  the  ridges  at  the  last-mentioned 
locality,  there  is  no  reason  to  question  the  statement  that  the  whole 
mud  plain  had  the  smooth  surface  common  to  tidal  flats  until  it  was 
disturbed  by  the  earthquake.  Nor  do  I find  any  room  for  doubt 
either  that  the  ridges  originated  as  waves  on  the  surface  of  the  mud 
while  it  was  rendered  quasi  liquid  by  violent  agitation,  or  that  they 
persisted  because  the  mud  promptly  resumed  its  normal  coherence 
when  the  agitation  ceased.  It  is  by  no  means  equally  clear  that  the 
arrested  waves  were  true  gravity  waves  rolling  across  the  mud  plain. 
Whatever  their  mechanism  and  history,  they  illustrate  a mode  of 
response  of  wet,  unconsolidated  material  to  powerful  earth  tremors, 
they  suggest  an  explanation  of  certain  wavelike  ridges  produced  on 
areas  of  made  ground  in  San  Francisco,  and  they  contribute  to  an 
understanding  of  the  peculiar  destructiveness  of  the  earthquake  in 
such  areas. 


THE  EFFECTS  OF  THE  EARTHQUAKE  AND  FIRE  ON 
VARIOUS  STRUCTURES  AND  STRUCTURAL 
MATERIALS. 


By  Richard  L.  Humphrey. 


GENERAL  DISCUSSION  OF  THE  EARTHQUAKE  CONDITIONS. 

On  the  18th  of  April,  1906,  the  whole  civilized  world  stood  aghast 
at  the  appalling  destruction  which  visited  the  city  of  San  Francisco 
and  vicinity.  Three  weeks  later,  for  the  purpose  of  studying  the 
effect  of  the  earthquake  and  fire  on  structural  materials,  the  writer 
began  the  investigation  herein  described,  lasting  six  weeks  and  cov- 
ering the  entire  affected  territory.  It  would  be  impossible,  however, 
to  describe  the  extent  of  the  damage  adequately  or  comprehensively 
in  a report  of  this  character.  When  we  consider  the  terrific  destruc- 
tion wrought  in  the  surface  of  the  earth  by  the  first  movement  or 
“ slip,”  which  developed  structural  weaknesses,  it  is  not  surprising 
that  this  movement  and  the  resulting  vibrations  should  prove  so 
fatal  to  the  structures  of  man. 

In  the  fire  that  followed  hundreds  of  thousands  of  people  were 
rendered  homeless  and  dependent  on  public  bounty  for  shelter  and 
the  necessities  of  life.  This  phase  of  the  disaster  appealed  to  popular 
sympathy  and  drew  spontaneously  from  all  parts  of  the  country 
contributions  of  food,  clothing,  household  furnishings,  and  money  for 
the  relief  of  the  destitute. 

To  the  user  of  the  materials  of  building  construction  the  study  of 
the  behavior  and  relative  efficiency  of  the  various  classes  of  such 
materials  under  the  unusual  and  rigorous  conditions  imposed  by  the 
earthquake  and  fire  is  most  interesting  and  instructive.  The  test  was 
one  of  such  violence  that  only  structures  of  first-class  design  and 
materials  and  honest  workmanship  could  survive.  Flimsy  and  loosely 
built  structures  collapsed  like  houses  of  cards  under  the  terrific 
wrenching  and  shaking,  and  many  of  the  structures  which  withstood 
the  earthquake  were  subjected  to  a second  test  in  a fire  which  surpassed 
all  the  great  conflagrations  of  recent  years.  Some  of  these  structures 
14 


GENERAL  DISCUSSION  OE  THE  EARTHQUAKE  CONDITIONS.  15 

which  successfully  withstood  the  first  test  failed  signally  under  the 
second,  by  reason  of  inadequate  fireproofing.  A very  few  withstood 
both  tests  successfully. 

It  is  a generally  accepted  fact  that  no  structure  could  have  with- 
stood the  stresses  produced  by  the  movement  of  the  earth  at  the 
“ fault  trace,’9  along  which  the  maximum  intensity  of  disturbance 
was  localized.  The  stresses  produced  by  the  vibrations  at  other  points, 
however,  could  have  been  resisted  with  safety  if  proper  design,  first- 
class  materials,  and  honest  workmanship — constituting  the  whole 
secret  of  earthquake-resisting  power — had  been  employed  in  the  struc- 
tures so  located.  In  tall  structures  rigidity  of  construction,  attained 
by  adequate  diagonal  and  portal  bracing,  is  absolutely  essential.  In 
such  buildings,  owing  to  the  inertia  of  the  mass  of  the  upper  portion, 
the  maximum  bending  moment  exerted  by  the  earthquake  was  ap- 
plied at  some  point  between  the  foundation  and  the  top — generally 
just  below  the  middle.  While  reenforced-concrete  structures  were 
few  in  the  zone  of  seismic  disturbances,  these  few  stood  the  test  by 
earthquake  and  fire  in  a highly  satisfactory  manner.  Rigidity  and 
stiffness  and  a high  fire  resistance  are  inherent  qualities  of  concrete, 
and  this  material  proved  admirably  suited  to  resist  these  extraordi- 
nary tests. 

The  destruction  -was  greatest  in  structures  built  on  filled  ground, 
or  on  alluvial  soils  in  the  valleys  of  rivers,  with  foundations  which 
did  not  go  through  to  solid  ground,  the  settling  of  the  earth  caused 
by  the  vibrations  resulting  in  permanent  displacement  or  distortion 
of  such  structures.  At  many  places  where  great  destruction  took 
place,  as  at  Palo  Alto,  San  Jose,  Salinas,  Santa  Rosa,  etc.,  the  struc- 
tures were  built  on  soft  ground.  In  structures  built  on  solid  ground 
or  rock  formation  the  action  was  much  less  severe  and  was  confined 
to  shaking,  producing  a maximum  oscillation  in  the  upper  portions 
of  the  structure. 

In  order  to  understand  properly  the  conditions  under  which  such 
destruction  as  that  caused  by  the  earthquake  could  occur,  one  should 
study  the  geologic  conditions  prevalent  just  prior  to  the  earthquake. 

The  history  of  the  Pacific  coast  is  replete  with  records  of  seismic 
disturbances,  the  entire  region  being  in  a condition  of  unstable 
equilibrium  and  cut  by  long  rifts  in  the  surface,  called  u faults,” 
which  have  produced  a series  of  long,  narrow  valleys.  The  forces 
which  produce  elevations  and  subsidence  of  the  surface  also  produce 
stresses,  which  finally  overcome  the  adhesion  of  the  opposing  rift 
walls,  and  earthquakes  take  place  in  the  slipping  of  these  walls, 
through  a few  inches  or  a few  feet,  in  the  effort  to  adjust  the  stresses. 
These  earthquakes  are  of  two  classes — volcanic  and  tectonic.  The 
former  occur  in  regions  of  volcanic  activity,  are  shallow  in  extent, 


16  THE  SAN  FRANCISCO  EAETHQUAKE  AND  FIEE. 

and  affect  comparatively  small  areas;  the  latter  not  only  extend  to 
a much  greater  depth,  but  also  affect  much  greater  areas.  The 
region  north  and  south  of  San  Francisco  is  regarded  as  particularly 
susceptible  to  earthquakes  of  the  latter  type. 

A.  C.  Lawson  has  traced  several  of  the  “ faults  ” referred  to,  and 
about  ten  years  prior  to  the  San  Francisco  earthquake  he  indicated 
the  location  of  the  present  fault  trace  south  of  the  Golden  Gate. 
His  relief  map  of  California  serves  to  show  the  lines  of  known  faults 
by  the  parallelism  of  the  ridges  and  valleys.  In  following  these 
valleys  one  finds  evidence  of  faulting  on  every  hand — the  scar&  and 
markings  on  the  earth  and  rocks,  and  the  presence  of  little  lakes  or 
ponds  without  visible  source  of  supply  other  than  the  watershed  of 
the  adjacent  ridges.  According  to  Lawson,  the  coast  of  California 
is  rising,  and  the  seismic  disturbances  whose  record  is  found  im  the 
rocks  have  been  produced  by  movements  in  the  process  of  upheaval 
and  subsidence,  of  folding  and  faulting,  which  are,  perhaps,  greater 
along  the  coast  of  California  than  in  any  other  part  of  the  world. 
Whatever  may  be  the  causes  of  these  movements,  it  is  apparent  that 
the  resultant  stresses  relieve  themselves  by  producing  these  faults 
or  rifts  in  the  earth’s  surface. 

The  average  Californian  becomes  accustomed  to  the  earthquakes 
which  produce  “ temblors  ” of  sufficient  intensity  to  rattle  windows. 
Prior  to  the  great  earthquake  of  April  18,  1906,  these  temblors 
were  of  frequent  occurrence,  but  occasioned  no  alarm  and,  indeed, 
scarcely  excited  a passing  interest.  Over  two  hundred  earthquakes 
were  recorded  during  the  period  from  1850  to  1886,  being  more 
prevalent  in  the  vicinity  of  San  Francisco  Bay  than  elsewhere.  The 
writer  is  informed  that  during  the  period  just  prior  to  April  18 
few  if  any  noticeable  temblors  occurred.  It  is  fair  to  assume,  there- 
fore, that  the  great  earthquake  resulted  from  an  accumulation  of 
stresses  which  would  ordinarily  have  been  relieved  by  smaller  move- 
ments. 

The  relative  intensities  of  earthquakes  are  indicated,  on  the  Rossi- 
Forel  scale,  by  Nos.  I to  X.  All  under  V produce  no  visible  destruc- 
tion, and  from  V the  destruction  increases  up  to  X,  which  represents 
those  in  which  complete  destruction  takes  place.  The  writer  under- 
stands that  the  earthquake  of  April  18  is  rated  at  IX  on  this  scale. 

This  earthquake,  the  most  severe  in  the  history  of  the  State,  took 
place  at  5 hours  13  minutes  and  38  seconds  a.  m.,  Pacific  time,  the 
main  shock  lasting  one  minute  and  five  seconds.  Between  this  time 
and  7 a.  m.  about  thirty  minor  shocks  were  recorded.  A zone  of 
destruction  50  miles  wide  was  produced,  extending  for  a distance  of 
150  to  200  miles  north  and  south  of  San  Francisco  (see  the  map,  fig.  1, 
p.  3),  beginning  at  Point  Arena,  paralleling  the  coast  to  Fort  Ross, 


EFFECTS  ON  STRUCTURES  OUTSIDE  OF  SAN  FRANCISCO.  17 

passing  under  the  ocean  bed  just  west  of  the  Golden  Gate,  reappear- 
ing on  the  land  at  Mussel  Rock,  and  following  the  Pilarcitos  and  San 
Andreas  pipe  lines  of  the  Spring  Valley  Water  Company  in  a direct 
line  to  Hollister.  The  zone  included  San  Francisco  Bay,  Russian 
River,  and  the  Sonora,  Santa  Clara,  and  Salinas  valleys.  The  first 
movement  was  along  this  zone  in  a southeasterly  direction,  and  the 
vibrations  set  up  on  all  sides  produced  a continuous  twisting,  rocking, 
wrenching  movement  that  brought  down  chimneys,  walls,  towers,  etc. 
In  the  opinion  of  the  California  earthquake  investigation  commission 
the  slip  commenced  at  the  northwest  end  of  the  zone,  and  the  force 
which  occasioned  the  rupturing  or  shearing  movement  was  a progress- 
ively decreasing  one  to  the  southeast  end.  As  in  the  earthquake  of 
1868,  the  destruction  was  greatest  in  proportion  to  the  nearness  to 
the  fault  trace,  and  in  parts  built  on  soft  or  alluvial  soil,  or  on  “ made 
ground.”  The  earthquake  as  recorded  by  the  seismographs  showed  a 
horizontal  movement  of  about  3 inches  and  a vertical  movement  of 
about  1 inch,  the  velocity  of  propagation  being  about  2.1  miles  per 
second.  The  wave  movement  was  long  and  slow  in  hard  soil  and 
rock  and  comparatively  short  and  incoherent  in  soft  ground. 

EFFECTS  ON  STRUCTURES  OUTSIDE  OF  SAN  FRANCISCO. 

In  considering  in  detail  the  damage  wrought  by  the  earthquake 
one  must  look  for  evidence  in  the  country  surrounding  San  Francisco, 
since  the  fire  in  that  city  obliterated  most  of  the  signs  of  the  damage. 

The  greatest  loss  in  the  city  of  San  Francisco  was  principally  the 
result  of  the  fire,  which  was  rendered  uncontrollable  owing  to  the 
wrecking  of  the  water-supply  system  by  the  earthquake.  (See  the 
maps  of  the  city  and  vicinity,  Pis.  LVI  and  LVIX.)  An  examination 
of  the  damage  to  the  system  at  once  suggests  itself,  especially  as  some 
of  the  main  conduits  are  located  on  or  near  the  fault  line. 

The  city  is  supplied  principally  by  gravity  from  three  main  dis- 
tributing reservoirs,  viz,  University  Mound,  College  Hill,  and  Lake 
Honda;  there  are  also  two  supplementary  sources — Alameda  Creek, 
on  the  east  side  of  the  bay,  and  Lake  Merced.  The  University  Mound 
reservoir,  having  a capacity  of  33,000,000  gallons,  is  supplied  from 
Crystal  Springs  Lake  through  17  miles  of  44-inch  wrought-iron  pipe, 
carried  for  a considerable  distance  on  trestles  over  the  marshes.  The 
College  Hill  reservoir  has  a capacity  of  15,000,000  gallons  and  is  sup- 
plied from  San  Andreas  Lake  through  14  miles  of  44-inch,  37-inch, 
and  30-inch  wrought-iron  pipe.  The  Lake  Honda  reservoir,  with  a 
capacity  of  31,000,000  gallons,  is  fed  from  Pilarcitos  Lake  through 
16  miles  of  conduit,  1J  miles  of  which  is  wooden  flume  and  the  re- 
mainder cast-iron  and  wrought-iron  pipe  and  brick  tunnel.  Of  the 
two  supplementary  supplies,  the  water  from  Alameda  Creek  is  car- 


18 


THE  SAN  FEAN CISCO  EAKTHQUAKE  AND  FIRE. 


r^ed  27  miles,  crossing  San  Francisco  Bay  through  submarine  pipes, 
and  thence  passing  through  the  Crystal  Springs  conduit  to  the  city ; 
that  from  Lake  Merced  is  pumped  into  the  Pilarcitos  conduit  and 
thence  to  the  city. 

In  company  with  Herman  Schussler,  chief  engineer  of  the  Spring 
Valley  Water  Company,  the  writer  made  a detailed  examination  of  the 
principal  conduits  and  reservoirs.  On  the  San  Bruno  marsh  the  44- 
inch  line  to  the  University  Mound  reservoir  had  been  thrown  off  the 
trestle  for  a distance  of  1,300  feet;  and,  while  the  pipe  was  readily 
repaired,  the  trestle  had  to  be  rebuilt,  as  many  of  the  timbers  had 
rotted.  Near  Baden  the  line  had  been  telescoped  42  inches,  shearing 
off  an  8-inch  gate  valve.  The  reservoir  itself  was  undamaged,  yet  its 
three  days’  supply  was  rendered  useless  by  the  breaks  in  the  cast-iron 
distributing  mains. 

The  only  damage  done  to  the  conduit  between  San  Andreas  Lake 
and  the  College  Hill  reservoir  was  at  Baden,  where  the  slip  joint  had 
been  broken,  tearing  out  the  four  cast-iron  lugs — an  effect  indicating 
a force  of  at  least  2,000,000  pounds. 

The  principal  breaks  in  the  Pilarcitos  conduit,  which  was  so  badly 
damaged  that  the  company  decided  to  abandon  it,  were  examined. 
This  conduit  had  been  located  for  convenience  in  one  of  the  long,  nar- 
row valleys,  and  therefore  on  the  line  of  an  old  fault.  It  is  evident 
that  it  would  be  futile  to  attempt  to  build  this  conduit  strong  enough 
to  withstand  a slip  on  the  fault  line.  The  breaks  in  this  30-inch 
wrought-iron  pipe  ranged  from  30  inches  to  G feet  in  length.  At 
other  points  it  was  telescoped  and  twisted  beyond  repair.  (See  PI. 
IX.)  The  Pilarcitos  conduit  crosses  Frawleys  Gulch  on  a trestle. 
The  movement  of  the  earth  produced  a compression  in  the  pipe  line 
at  this  point,  which  threw  it  off  and  wrecked  the  trestle,  and  the  water 
in  the  conduit  leading  to  the  trestle  line  was  released  so  rapidly  that 
it  formed  a vacuum,  which  caused  this  conduit  to  collapse,  as  shown 
in  PI.  X,  A.  The  conduit  crosses  and  recrosses  the  fault  for  a dis- 
tance of  6 miles  south  of  Frawleys  Gulch.  The  30-inch  wrought- 
iron  pipe  line  was  torn  and  twisted  at  each  crossing,  while  the  earth 
dam  of  Pilarcitos  Lake  was  uninjured. 

The  San  Andreas  earth  dam  lies  across  the  fault,  the  crossing  being 
about  100  feet  from  its  east  end,  and  the  dam  shows  a disturbance  for 
a distance  of  more  than  100  feet.  One  of  the  worst  cracks  runs  diag- 
onally across  a culvert  4 feet  6 inches  in  diameter,  which  appears  to 
be  uninjured.  Although  San  Andreas  Lake  had  considerable  water 
in  it,  no  appreciable  loss  of  head  was  observed.  There  is  a roadway 
over  the  dam,  along  which  runs  a fence.  Both  were  offset  at  the 
fault  line  about  3J  feet.  A wooden  flume  used  for  diverting  storage 
water  to  the  reservoir  lines  crosses  the  fault,  and  was  wrecked  at  that 


EFFECTS  ON  STRUCTURES  OUTSIDE  OF  SAN  FRANCISCO.  19 

point  for  50  feet.  A brick  conduit  used  for  waste  purposes  extends 
across  the  fault.  All  the  four  rings,  of  hard-burned  brick,  are  laid 
in  first-class  Portland-cement  mortar,  making  a first-class  piece  of 
work  in  every  way.  This  conduit,  which  is  9 feet  6 inches  in  diam- 
eter, was  crushed  together  at  the  crossing. 

The  Searsville  dam,  a structure  similar  to  the  San  Andreas  earth 
dam,  1 mile  east  of  the  fault  line  and  parallel  to  it,  was  also  found 
to  be  uninjured. 

Very  little  damage  was  done  to  the  pumping  stations,  and  the  steel 
standpipes  of  this  company  were  not  injured.  The  Lake  Honda 
reservoir  was  slightly  damaged  by  a crack  in  its  concrete  lining.  No 
damage  was  done  to  the  Alameda  Creek  supply,  except  to  the  con- 
nection at  the  Belmont  pumping  station. 

The  concrete  dam  near  San  Mateo,  at  the  lower  end  of  Crystal 
Springs  Lake,  parallel  to  the  fault  line  and  a few  hundred  feet  east 
of  it,  was  undamaged.  This  dam,  a view  of  which  is  given  in  PI. 
XI,  B , is  built  of  large  blocks  of  concrete,  thoroughly  keyed  together 
and  molded  in  place,  each  block  containing  between  200  and  300  cubic 
feet.  The  dam  is  680  feet  long,  with  a present  height  of  146  feet. 
When  completed  it  will  be  170  feet  high,  176  feet  thick  at  the  base, 
and  25  feet  thick  at  the  top.  It  is  arched  upstream  to  a radius  of 
637  feet. 

The  clay-core  earth  dam  of  the  upper  Crystal  Springs  Lake  lies 
across  the  fault  line  at  nearly  right  angles.  This  dam  is  now  main- 
tained as  a county  causeway,  equalizing  pipes  having  been  placed 
through  it.  At  the  time  of  the  earthquake  the  water  was  at  the  same 
height  on  each  side,  and  the  absence  of  any  “ head  ” made  it  impos- 
sible to  tell  the  extent  of  the  damage.  The  dam  moved  about  6 feet, 
however,  this  fact  being  shown  clearly  by  an  offset  of  that  amount  in 
the  fence  which  runs  across  it.  The  roadway  over  the  dam  also 
shows  the  same  offset,  although  not  so  clearly. 

The  water  supply  of  San  Francisco,  as  compared  with  that  of  other 
cities,  was  fairly  good  and  had  a rated  capacity  of  36,000,000  gallons 
per  day.  The  failure  to  control  the  fire  by  reason  of  the  crippling 
of  the  water  supply  was  not  due  to  the  failure  of  the  system  outside 
of  the  city,  but  to  the  breaks  in  the  distributing  mains  within  the 
city,  which  ^rendered  unavailable  about  80,000,000  gallons  of  water 
stored  within  the  city  limits.  These  breaks  occurred  (see  the  map, 
PL  LVI)  wherever  the  pipes  passed  through  soft  or  made  ground. 
No  breaks  occurred  where  the  cast-iron  pipe  was  laid  in  solid  ground 
or  rock.  It  is  evident  that  in  earthquake  countries  water-supply 
pipes,  at  least,  should  be  so  laid  as  to  avoid  the  action  of  slips,  set- 
tling, and  ground  movements  of  all  kinds.  The  pipe  lines  should 
also  be  arranged  with  gates  and  by-passes,  making  it  possible  to  cut 


20  THE  SAN  FEAN CISCO  EAKTHQUAKE  AND  FIRE. 

out  any  portion  of  the  system  which  may  become  crippled.  There 
should  also  be  some  means  of  preventing  the  loss  of  water  which  is 
occasioned  by  breaks  in  the  house  service  pipes. 

While  one  of  the  main  conduits  was  badly  damaged  wherever  it 
crossed  the  fault,  this  damage  was^  no  greater  than  that  done  to  any 
other  structure  that  was  situated  at  the  fault  line.  Structures  so 
located  were  torn  apart,  the  gap  in  the  case  of  a fence  (PL  I,  B)  or 
road  (PL  I,  A)  being  from  6 to  20  feet,  according  to  local  conditions. 
In  the  country  around  Fort  Eoss  there  were  many  trees  located  on 
the  fault  that  showed  the  effect  of  the  slip.  Great  redwood  and 
pine  trees  were  either  twisted  out  of  normal  position  or  split  (Pl.  II) 
from  the  roots  up  for  distances  of  85  feet  or  more,  even  when  per- 
fectly sound.  This  splitting  action  was  due  to  the  earth  on  the  west 
of  the  line  of  faulting  moving  the  roots  on  that  side,  a motion  which 
tended  to  pull  the  tree  apart.  Where  the  tree  had  some  defect  or 
was  unsound  (as  from  dry  rot)  the  action  was  even  more  marked 
and  the  destruction  much  greater.  Eedwood  trees  grow  to  great 
heights  and  are  perfectly  straight,  and  to  find  one  out  of  plumb  is 
very  unusual. 

Another  interesting  example  of  the  effect  of  the  slip  along  the 
line  of  the  fault  is  afforded  by  the  Southern  Pacific  Eailroad  bridge 
over  Pajaro  Eiver  near  Chittenden  station.  This  bridge  crosses  the 
fault  obliquely  at  a very  acute  angle — about  10°.  It  consists  of  two 
girder  shore  spans  of  50  feet  each  and  three  Pratt  truss  river  spans 
of  about  100  feet  each.  The  piers  and  abutments  are  built  of  con- 
crete, with  granite  coping  and  bridge  seats  (Pl.  XI,  A).  The  bridge 
was  badly  racked  by  the  movement  of  the  earth,  which  dragged 
the  piers  and  abutments.  The  movement  of  the  south  abutment 
was  about  24  inches,  a distance  sufficient  to  leave  the  girder  with- 
out support.  The  ground  also  moved  a greater  distance  than  the 
abutment — perhaps  8 or  10  inches  farther.  The  movement  of  the 
earth  tending  to  pull  the  piers  from  under  the  trusses  was  resisted 
by  the  anchor  bolts,  resulting  in  a cracking  of  the  piers,  appar- 
ently on  the  lines  marking  the  different  daily  batches  of  concrete 
used  in  constructing  them.  The  granite  caps  were  moved  out  of 
position  and  many  of  them  cracked,  and  the  anchor  bolts  were  twisted 
and  bent.  The  bridge  was  put  into  service  by  the  construction  of  a 
timber  support. 

In  the  vicinity  of  Los  Gatos,  where  the  line  of  faulting  passes 
through  the  Santa  Cruz  Mountains,  it  crosses  the  first  tunnel  of  the 
narrow-gage  railroad  to  Santa  Cruz  near  Wrights.  In  this  tunnel 
a portion  of  the  loose  roof,  of  shale  on  a layer  of  serpentine  or  soap- 
stone, caved  in,  completely  closing  the  tunnel.  A house  on  this  fault 
line  near  Wrights  was  split  in  twain,  the  movement  of  the  earth 
throwing  the  west  side  of  the  house  from  its  foundation  (Pl.  X,  B). 


EFFECTS  ON  STRUCTURES  OUTSIDE  OF  SAN  FRANCISCO. 


21 


The  Saratoga  reservoir  of  the  San  Jose  Water  Company  lies  in  a 
saddle  of  the  Santa  Cruz  Mountains  between  Saratoga  and  Los  Gatos, 
and  the  fault  line  crosses  it  at  right  angles,  the  cracks  extending 
through  the  body  of  the  dam.  The  reservoir  was  full  at  the  time, 
but  there  was  no  apparent  loss  of  head. 

As  already  stated,  in  the  country  bordering  the  line  of  faulting  the 
damage  done  was  greater  in  soft  or  alluvial  soil  or  made  ground. 
Most  wooden  water  tanks  on  low  supports  were  wrecked,  not  only  in 
the  vicinity  of  the  fault  line  but  throughout  the  affected  zone,  the 
failure  being  due  to  a lack  of  lateral  bracing  of  the  trestle  support. 
Chimneys  generally  collapsed,  the  cause  being  the  unequal  movement 
of  the  inelastic  brickwork  and  the  usually  elastic  frame  structure 
surrounding  it.  Wooden  buildings  on  good  foundations  stood  well,  the 
chief  damage  being  to  the  chimneys  and  plastering.  The  alluvial 
or  soft  soil  forming  the  banks  of  rivers  generally  moved  toward  the 
river  under  the  earthquake  vibrations,  the  settling  of  the  ground 
being  most  marked  (PI.  VIII,  B).  The  country  in  the  vicinity  of 
Salinas  Liver  presented  interesting  features  of  this  character.  The 
county  road  crosses  the  river  near  Salinas  on  a wooden  bridge,  and 
the  slipping  of  the  banks  carried  the  south  abutment  6 feet  toward 
the  river.  The  ground  was  badly  cracked  and  there  were  a number  of 
slips  in  the  neighborhood.  The  road  leading  to  Spreckels’s  sugar 
mill,  4 miles  south  of  Salinas,  was  also  greatly  damaged  by  the  slips. 
Spreckels’s  sugar  mill  (PI.  XII,  A)  is  located  on  soft  alluvium.  The 
main  building,  which  is  500  feet  long,  is  said  to  be  the  largest  sugar 
mill  in  the  world.  The  vibrations  of  the  earth  jarred  the  brickwork 
loose  at  the  end  of  the  building,  which  buckled  in  the  middle,  where 
there  were  no  floors  above  the  second  floor.  The  damage  to  other 
buildings  was  also  extensive.  The  town  of  Salinas  itself  was  severely 
shaken.  The  high-school  building  and  some  of  the  buildings  on  the 
main  street  were  damaged,  chimneys  were  thrown  down,  and  a water 
tank  of  the  Southern  Pacific  Railroad,  supported  on  a steel  trestle 
near  the  station,  collapsed. 

Along  the  Bay  of  Monterey  the  whole  shore  slipped  about  12  feet 
into  the  bay,  the  movement  buckling  the  rails  on  a railroad  trestle 
and  the  cars  dropping  about  5 feet.  A frame  house  and  surroundings 
moved  12  feet,  still  maintaining  their  relative  positions.  In  Mon- 
terey the  principal  damage  was  in  the  loss  of  chimneys  and  cracking 
of  plaster. 

At  San  Jose,  located  on  the  soft  alluvium  of  the  Santa  Clara 
Valley,  the  destruction  was  extensive.  The  post-office,  a very  sub- 
stantial building,  lost  its  tower,  which  was  laid  up  in  lime  mortar, 
and  was  deficient  in  lateral  bracing.  The  walls  were  of  brick  with 
a 4-inch  or  6-inch  stone  veneer,  and  there  was  a wooden-framed  slate- 
covered  apex.  The  collapse  of  the  tower  damaged  the  pavement,  and 
7171— Bull.  324—07 3 


22  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

to  some  extent  the  building  itself.  The  damage  to  the  hall  of 
records,  along  the  end  walls,  was  due  entirely  to  defective  construc- 
tion. The  Hall  of  Justice  (PL  XII,  Z?),  which  was  completed  in 
1905,  had  the  wall  along  the  cornice  line  thrown  down.  The  reen- 
l'orced-concrete  roof  contributed  no  little  to  the  support  of  the  walls 
of  the  building,  and  had  the  stonework  been  less  heavy  and  of  better 
quality  the  damage  probably  would  not  have  been  so  extensive.  The 
high  school  (PL  XIII,  Z>),  a flimsy  structure  of  brick  with  wooden 
frame,  was  so  badly  wrecked  that  it  had  to  be  torn  down  as  a matter  of 
safety.  The  destruction  of  the  buildings  along  First  street,  the 
principal  business  thoroughfare,  was  also  extensive.  Lime  mortar, 
flimsy  framing,  poor  design,  and  lack  of  tie  between  floor  and  roof 
members  and  walls  were  the  causes  of  these  failures. 

Perhaps  the  worst  example  of  poor  design,  bad  workmanship, 
and  poor  materials  in  the  earthquake  territory,  except  in  the  city 
of  San  Francisco,  is  the  insane  asylum  at  Agnew,  about  6 miles 
northwest  of  San  Jose,  consisting  of  a main  building  surrounded  by 
a number  of  others — all  flimsily  constructed  brick  structures  with 
timber  frames.  The  construction  of  these  buildings,  with  their 
thin  walls  (in  many  places  devoid  of  mortar)  and  light,  insufficient 
wooden  framing,  indicates  a criminal  negligence  that  is  appalling. 
One  hundred  and  seventeen  patients  and  attendants  lost  their  lives, 
principally  from  the  fall  of  the  central  tower  of  the  main  building. 
The  brick  stack  of  the  power  plant  and  the  towers  of  surrounding 
buildings  collapsed.  In  the  farmyard  near  by  is  a water  tank 
supported  on  a wooden  trestle.  This  tank  moved  about  10  inches, 
while  less  than  a stone’s  throw  away  are  four  water  tanks  supported 
by  a diagonally  braced  steel  trestle,  which  were  undamaged  (PL 
XIII,  A). 

The  most  interesting  ruins  are  those  of  the  Leland  Stanford  Junior 
University,  at  Palo  Alto,  6 miles  east  of  the  fault  line.  These  build- 
ings were  on  a soft  soil  and  were  therefore  subjected  to  the  severest 
earthquake  conditions;  and  as  they  represent  several  different  types 
of  construction  they  afford  a profitable  study  in  the  earthquake- 
resisting  power  of  various  structures  and  structural  materials.  The 
destruction  was  very  great,  most  of  the  buildings  being  wholly  or 
partially  destroyed. 

Three  types  of  wall  construction  were  represented — (1)  solid 
stone,  (2)  brick  and  stone  veneer,  and  (3)  reenforced  concrete.  The 
buildings  of  the  first-mentioned  type,  which  were  erected  by  Senator 
Stanford  by  day  labor,  were  examples  of  good  substantial  work,  and 
the  damage  to  them  was  not  so  great.  The  stone-veneer  buildings 
represent  a later  type,  resorted  to  as  a matter  of  cheapness,  and  suf- 
fered the  most.  The  third  type,  of  reenforced  concrete,  sustained 
practically  no  damage.  The  stone-veneer  buildings  have  a 4-inch  or 


EFFECTS  ON  STRUCTURES  OUTSIDE  OF  SAN  FRANCISCO.  23 

6-inch  face  of  stone,  poorly  bedded,  containing  a large  percentage  of 
spalls,  the  lime  mortar  being  of  good  quality.  The  construction  is 
fairly  common  in  other  parts  of  the  country.  The  roof  trusses  were 
not  anchored  to  the  walls,  but  to  a great  extent  were  butted  against 
the  walls;  the  floor  joists  rested  in  the  walls  and  were  not  tied. 
Under  the  vibrations  the  walls  were  pushed  out  of  plumb  and,  having 
no  proper  connection  with  the  floor  and  roof  members,  collajpsed. 

The  gymnasium  and  library  presented  interesting  features.  The 
dome  of  the  library  was  supported  by  a skeleton  of  jsteel,  and  although 
the  surrounding  walls  collapsed,  this  dome  Avas  not  damaged  (PI.  XV, 
A ) . The  gymnasium  dome  rested  on  intermediate  brick  walls,  which 
collapsed  with  the  dome  (PI.  XV,  B). 

The  boys’  dormitory  (Encina  Hall)  was  built  of  stone,  and  was  one 
of  the  buildings  erected  by  Senator  Stanford.  The  chimneys  of  this 
structure  collapsed  and  crashed  through  the  roof  and  floors,  killing  one 
student  and  injuring  several  others.  The  walls  themselves  were  but 
slightly  cracked.  The  girls’  dormitory  (Roble  Hall)  had  Avails  of 
reenforced  concrete  with  wooden  floors.  The  chimneys  on  this  struc- 
ture also  collapsed,  but  no  other  damage  was  done,  the  walls  being  left 
intact,  without  any  cracks. 

The  memorial  arch  (PI.  XVI)  was  a poorly  designed  structure, 
100  feet  high,  Avith  stone-veneered  walls.  The  structure  above  the 
arch  ring  was  hollow,  and  an  attempt  had  been  made  to  stiffen  it  by 
the  use  of  a number  of  I beams.  These  beams  were  not  tied  to  the 
stonework,  but  simply  rested  upon  it,  and  under  the  action  of  the 
earthquake  they  became  battering  rams  and  helped  to  accomplish  the 
destruction  of  the  arch.  The  arch  as  first  designed  was  75  feet  high, 
and  it  will  be  noted  that  the  earthquake  reduced  it  to  the  height  orig- 
inally intended  (PI.  XVI,  B). 

The  memorial  chapel,  one  of  the  most  beautiful  buildings  in  this 
country,  was  almost  completely  wrecked  (PI.  XVII,  B)  by  the  col- 
lapse of  the  tower.  A platform  of  steel  beams  had  been  placed  under 
the  clock  as  a precaution  against  the  chance  falling  of  the  pendulum, 
and  this  platform  saved  the  clock.  The  damage  done  to  the  mosaic 
work  and  the  interior  decoration  is  probably  irreparable. 

The  chemical  laboratory  was  damaged  by  falling  chimneys,  and 
gable  walls  were  pushed  out  and  suffered  considerable  damage  by  the 
collapse  of  the  assay  stack.  The  plastering  Avas  also  badly  cracked. 
Great  damage  was  also  wrought  in  the  poAver  plant  of  the  mechanical 
engineering  department  by  the  falling  of  the  stack. 

The  quadrangle,  or  main  academic  portion  of  the  university,  was 
built  by  day  labor  and  was  a fair  piece  of  work.  The  cloister  (PI. 
XVIII,  B)  suffered  considerably,  the  bases  and  caps  of  the  columns 
being  spalled  and  chipped,  indicating  that  they  must  haA^e  been  sub- 
jected to  a rocking  motion.  The  arches  apparently  opened  up,  for  in 


24 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  EIRE. 


a number  of  them  the  arch  stones  had  dropped  partly  out  of  place. 
The  department  of  geology  (PI.  XVIII,  A ),  the  newly  completed  end 
of  the  quadrangle,  suffered  the  greatest  damage;  many  of  the  walls 
will  have  to  be  rebuilt,  having  been  either  cracked  very  badly  or 
destroyed  entirely.  The  plastering  was  badly  cracked  and  showed 
the  outline  of  each  sheet  of  metal  lath.  Where  reenforced  concrete 
was  used  the  ceilings  were  free  from  cracks. 

The  most  interesting  building  is  the  museum  (PI.  XIV,  A),  which  . 
consists  of  a central  pavilion  of  reenforced  concrete  and  wings  of 
brick  plastered  with  cement  mortar.  The  columns  of  the  central 
pavilion  are  solid  concrete,  having  been  cast  in  place.  This  building 
had  wooden  floors.  The  wings  were  wrecked  by  the  earthquake,  but 
the  central  pavilion  escaped  injury,  although  its  contents  were  more 
or  less  damaged,  principally  by  being  shaken  from  their  positions. 

Although  the  destruction  at  Stanford  University  was  very  great, 
the  character  of  construction  was  fair  and  did  not  suffer  by  com- 
parison with  that  used  in  other  parts  of  the  country.  The  excellent 
qualities  of  reenforced  concrete  and  its  ability  to  withstand  earth- 
quake shock  were  strongly  demonstrated. 

The  town  of  Palo  Alto  suffered  considerably  from  the  earthquake. 
Chimneys  were  generally  thrown  down.  A number  of  buildings 
were  wholly  or  partly  wrecked,  the  causes  of  the  failures  being 
similar  to  those  in  other  sections,  consisting  largely  of  defects  in  de- 
sign, lack  of  adequate  bracing,  poor  mortar,  and  bad  workmanship. 
Three  concrete-block  buildings  were  either  wholly  or  partly  destroyed 
and  have  especial  interest,  since  they  have  been  cited  as  evidence  of 
the  failure  of  concrete  blocks.  Two  of  these  buildings  are  located  on 
Alma  street  opposite  the  station  and  on  opposite  sides  of  University 
avenue — the  Thiele  Building  (PI.  XVII,  A),  a partially  completed 
three-story  structure,  which  was  entirely  wrecked,  and  the  Fuller 
Building,  a two-story  structure,  which  also  collapsed.  The  concrete- 
block  walls,  13  inches  thick,  laid  in  cement  mortar,  were  not  braced 
in  any  way — the  joists,  1J  by  13,  simply  resting  upon  the  wall.  When 
the  building  vibrated,  the  wall  was  pushed  out  and  collapsed  because 
there  was  nothing  to  restore  it  to  its  normal  position.  This  defect 
was  more  clearly  shown  in  the  one-story  building  of  Vandervoort 
Brothers  (PI.  XIX,  />),  in  which  the  roof  truss  was  simply  butted 
against  the  block  wall  without  tie  or  other  connection. 

At  Santa  Ilosa  the  destruction  was  greater  than  in  any  other  section 
affected  by  the  earthquake,  and  the  fire  that  followed  completely 
wiped  out  the  business  section  of  the  town,  which  suffered  a greater 
proportionate  total  loss' than  San  Francisco.  A concrete-block  build- 
ing (PI.  XIX,  A)  in  this  town  escaped  with  slight  damage  at  the 
cornice  only,  where  the  blocks  were  thrown  down,  the  reason 
being  that  the  walls  were  tied  to  the  roof  timbers  by  tie-rods  which 


GENERAL  EARTHQUAKE  CONDITIONS  AND  EFFECTS. 


25 


held  the  walls  and  roof  together  and  made  them  move  as  a unit. 
The  cornice  was  rebuilt  before  the  view  was  taken.  While  buildings 
of  brick  and  stone  collapsed  all  around  this  one,  it  received  practi- 
cally no  damage  and  demonstrated  that  structures  that  will  success- 
fully withstand  earthquake  shock  can  be  built  of  concrete  blocks. 
The  other  buildings  at  Santa  Rosa  did  not  present  any  interesting 
features,  as  they  were  mostly  defective  in  design  and  workmanship 
and  the  material  was  generally  poor.  The  city  hall,  the  court-house 
(PL  XIV,  B ),  the  Masonic  Temple,  the  Keegan-Brush  Building,  and 
the  St.  Rose  Hotel  were  all  completely  wrecked,  and  added  their 
testimony  against  poor  mortar  in  brickwork,  light  wooden  frames, 
and  insufficient  bracing. 

Towns  like  Berkeley  and  Oakland  did  not  suffer  as  greatly  from 
the  earthquake  as  many  neighboring  towns,  the  reason  lying  in  the 
fact  that  these  towns  are  built  on  solid  ground  or  on  rock.  In  Berke- 
ley, while' chimneys  were  shaken  down,  there  was  no  extensive  earth- 
quake damage.  The  Greek  Theater,  a massive  structure  of  concrete, 
was  uninjured.  In  Oakland,  however,  greater  destruction  occurred. 
Just  outside  of  Oakland  is  located  the  Mills  College  for  Girls.  The 
science  building  had  brick  walls  plastered  with  cement  mortar, 
and  was  considerably  damaged  by  the  shaking  it  received  and  the 
falling  chimneys.  The  building  had  wooden  floors  and  was  con- 
siderably racked,  the  walls  being  pushed  out  slightly.  Within  a few 
feet  is  the  bell  tower  (PI.  XX,  B) , a reenforced-concrete  structure 
80  feet  high  with  walls  4 inches  thick,  which  was  not  damaged  in  the 
slightest  degree. 

CONDITIONS  IN  SAN  FRANCISCO. 

GENERAL  EARTHQUAKE  CONDITIONS  AND  EFFECTS. 

Within  the  city  of  San  Francisco  (see  the  map,  PI.  LVI)  the  havoc 
wrought  by  the  earthquake  depended  on  the  character  of  the  con- 
struction and  its  foundation.  Bordering  San  Francisco  Bay,  from 
Telegraph  Hill  to  Mission  Creek,  the  land  consists  of  mud  flats,  which 
have  been  gradually  filled  in,  and  on  this  land  many  large  com- 
mercial buildings  had  been  erected,  among  others  being  the  Union 
Ferry  building,  the  post-office,  the  mint,  and  the  custom-house. 
Adjoining  this  filled  land  was  comparatively  level  ground  composed 
of  sand  and  clay  formed  by  the  wearing  away  of  the  hillsides  and  by 
the  incoming  sand  from  the  seacoast — a fringe  of  soil  on  which  were 
located  many  of  the  principal  buildings.  From  Telegraph  Hill 
southwestward  along  Russian  Hill  to  Sutro  Fleights  runs  a ridge  of 
rocky  hills  composed  of  indurated  clay  shale,  with  serpentine  and 
other  rocky  formations  on  their  highest  summits. 


26  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

The  signs  of  destruction  wrought  by  the  earthquake  in  the  city  of 
San  Francisco  were  more  or  less  obscured  or  in  many  places  entirely 
obliterated  by  the  fire.  The  best  evidence  of  the  earthquake  can 
therefore  be  obtained  outside  the  burned  district,  and  the  following 
notes  cover  the  most  important  examples  of  damage  due  to  the 
earthquake  alone. 

As  in  districts  outside  of  San  Francisco,  the  greatest  damage  was 
done  to  those  structures  having  insufficient  foundations  built  on  soft 
alluvium  or  filled  ground.  The  settling  of  the  ground  in  the  mud 
flats  along  San  Francisco  Bay  and  of  the  filled  ground  in  old  water 
courses  was  accompanied  with  great  destruction.  It  was  in  such 
ground  that  the  greatest  number  of  breaks  occurred  in  the  cast-iron 
gas  and  water  mains  and  the  sewers.  The  breaks  in  the  sewers  were 
not  so  evident  as  those  in  the  gas  and  water  mains,  for  the  reason  that 
the  latter  were  under  pressure  and  breaks  in  them  resulted  in  breaks 
in  the  streets  themselves.  The  most  noticeable  destruction  resulting 
from  the  settling  of  soft  or  filled  ground  occurred  in  Howard  and 
Shotwell  streets  between  Seventeenth  and  Eighteenth  streets,  Bryant 
street  betwen  Ninth  and  Tenth  streets,  Dore  street  between  Bryant 
and  Brannan  streets  (PI.  VI,  A ),  and  at  the  corner  of  Seventh 
and  Mission  streets.  The  settling  was  greatest  in  Howard,  Dore,  and 
Bryant  streets,  being  in  Dore  street  at  least  5 feet. 

On  solid  ground  the  earthquake  had  a rocking  effect  which  pro- 
duced X cracks  (PI.  XXII,  A)  in  the  brick  or  stone  walls  of  those 
buildings  which  were  deficient  in  diagonal  bracing.  This  was  espe- 
cially true  in  .the  upper  stories  of  tall  buildings,  the  cracks  generally 
appearing  in  the  piers  between  windows  or  around  doorways.  The 
brick  curtain  walls  of  buildings  well  braced  diagonally,  brick  walls 
reenforced  with  band  iron,  and  well-buttressed  brick  walls,  as  in  such 
old  structures  as  the  Palace  Hotel,  Sailors’  Home,  St.  Mary’s  Hos- 
pital, Synagogue  Emanuel  (PI.  XXI,  Z>),  and  others,  and  walls  of 
reenforced  concrete  proved  best  adapted  to  withstand  this  rocking 
action.  The  Palace  Hotel  was  stiffened  with  cross  walls  in  addition 
to  the  band-iron  reenforcement  in  the  brickwork,  and  is  in  good  con- 
dition as  far  as  earthquake  effects  are  concerned.  It  was  completely 
gutted  by  fire,  however  (Pis.  XXX,  B;  LII,  Z?),  being  a nonfire- 
proof  structure  with  wooden  floors  and  roof  which  yielded  readily. 

Weak  and  flimsy  framing,  insufficient  bracing,  and  poor  mortar 
were  the  cause  of  most  of  the  failures  in  San  Francisco.  The  Albert 
Pike  Memorial,  a recently  completed  building  on  Geary  street  west 
of  Fillmore,  was  seriously  damaged,  and  so  also  was  the  adjoining 
Jeivish  synagogue  (PI.  XXI,  A) , which  had  not  been  quite  completed. 
Both  buildings  are  examples  of  defective  design  and  workmanship. 
In  the  girls’  high  school  the  damage  to  the  brick  walls  resulted  from  a 
lack  of  proper  tie  between  the  floor  and  roof  timbers  and  the  walls 


GENERAL  EARTHQUAKE  CONDITIONS  AND  EFFECTS.  27 

and  the  poor  quality  of  the  mortar  used  in  the  brickwork.  Again, 
in  the  Hahnemann  Medical  College,  on  California  street  near  Maple 
street,  the  destruction  of  the  end  walls  was  the  result  of  bad  design, 
the  roof  trusses  butting  against  the  walls  and  the  floor  timbers  resting 
upon  the  walls  without  adequate  tie.  The  poor  quality  of  the  mor- 
tar permitted  a ready  disintegration  of  the  brick-veneered  walls, 
although  some  band  iron  had  been  used  for  the  purpose  of  strength- 
ening them.  The  Cathedral  of  St.  Dominic,  with  its  high,  unbraced 
brick  walls  and  its  peculiar  wood-sheathed  spires,  also  proved  a 
victim  of  poor  design  and  workmanship ; the  sheathing  on  the  spires 
was  shaken  off  and  the  collapse  of  the  walls  resulted  in  extensive 
damage  to  the  interior. 

In  interesting  contradistinction  to  these  failures  was  the  Sailors’ 
Home,  erected  in  1858  for  use  as  a marine  hospital  and  condemned 
as  unsafe  after  the  earthquake  of  1868.  Its  heavy  brick  walls,  reen- 
forced with  band  iron  and  further  stiffened  by  cross  walls  thoroughly 
bonded,  are  in  excellent  condition.  The  building  rests  upon  rock 
and  the  framing  is  excellent;  the  rafters  are  fastened  to  a wall 
plate  which  ties  the  walls,  causing  the  structure  to  move  as  a unit. 
The  only  cracks  occurred  where  partition  walls  which  had  been  added 
were  shaken  loose  from  the  main  walls  and  around  the  archways 
leading  to  the  main  stairway  on  the  second  and  third  floors,  where 
no  extra  stiffening  of  the  walls  had  been  provided.  The  building  in 
all  other  respects  suffered  no  damage,  there  being  no  new  cracks 
apparent  in  the  exterior  walls. 

The  old  red-tiled  Spanish  Mission  Dolores  (PI.  XXIII,  B ),  built 
in  1777,  with  its  adobe  walls  and  wooden  frame,  was  not  injured, 
while  its  more  modern  successor  was  greatly  damaged.  The  com- 
plete collapse  of  the  tower  of  the  new  Mission  Dolores  was  not 
brought  about  directly  by  the  earthquake,  but  the  damage  was  such 
that  the  tower  had  to  be  taken  down,  as  shown  in  PL  XXIII,  B. 

The  group  of  buildings  comprising  the  plant  of  the  San  Francisco 
Gas  and  Electric  Light  Company,  built  on  the  soft  ground  along 
San  Francisco  Bay  just  west  of  Fort  Mason,  was  badly  shaken,  and 
none  of  the  buildings  escaped  damage.  The  collapse  of  the  stack 
wrecked  the  light  slate-covered  iron  roof  of  the  power  house  and 
started  the  fire  that  destroyed  the  roof  of  the  boiler  house.  The 
ground  settled  very  considerably  under  the  vibrations  of  the  earth- 
quake, and  further  destruction  was  caused  by  the  unequal  settling 
of  the  building.  The  main  shock  appeared  to  come  from  the  north, 
and  the  north  walls  received  the  greatest  damage.  The  end  wall  of 
the  retort  house  was  pushed  out  1 foot  at  the  center,  but  was  saved 
from  collapse  by  the  tie-rods  which  held  it  to  the  roof  truss.  The 
walls  were  cracked  at  the  northwest  and  northeast  corners.  The 
scrubber  and  gas-tar  holder  houses  were  wrecked,  the  heavy  wooden 


28 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


roof  trusses  collapsing.  Nearly  every  wall  was  moved  slightly,  but 
the  brickwork  was  generally  very  good,  and  apparently  had  cement  in 
it.  The  exhaust  house  had  three  intermediate  walls,  18  inches  thick 
at  the  top.  The  north  wall  and  the  next  one  fell  into  the  building, 
the  side  walls  being  pushed  out  6 inches.  The  building  had  wooden 
roof  trusses  and  the  north  truss  cracked  at  the  center  mortise.  The 
door  settled  badly  around  the  condensers.  The  gas  holder  collapsed 
from  the  sudden  release  of  the  gas  due  to  a break  in  the  mains.  The 
trestle  pier  extending  into  the  bay  also  collapsed. 

Most  of  the  structures  built  on  piles  along  the  bay  suffered  consid- 
erable damage,  especially  the  frame  sheds  on  the  wharves.  The 
Union  Ferry  Building  (PI.  XLVI,  X),  the  terminus  for  all  the  fer- 
ries plying  on  the  bay,  is  built  on  piles.  It  was  more  seriously  dam- 
aged by  the  earthquake  than  would  appear  at  first  sight,  and  barely 
escaped  the  fire  also.  It  is  of  interest  to  consider  in  some  detail  the 
behavior  of  this  structure  under  the  action  of  the  earthquake.  The 
ten-story  tower  was  so  seriously  damaged  as  to  require  the  removal  of 
the  masonry  walls,  and  will  probably  have  to  be  rebuilt.  This  tower 
consists  of  a steel  frame  which  was  inclosed  with  heavy  sandstone 
walls  backed  with  brick  for  several  of  the  lower  stories,  and  with 
sheet  metal  above.  The  floors  above  the  masonry  part  were  of  stone 
concrete  reenforced  with  expanded  metal  between  I beams.  The  brick 
walls  were  badly  shattered,  and  a large  section  was  throAvn  out  just 
below  the  clock  on  the  west  front,  while  on  the  east  front  a large  mass 
fell  through  the  skylight  onto  the  upper  story  of  the  main  building. 
There  were  but  few  cracks  in  the  north  and  south  walls.  The  steel 
time-ball  staff  was  badly  bent,  indicating  a considerable  movement  of 
the  top  of  the  tower,  probably  resulting  from  the  first  shock.  The 
steel  work  was  severely  racked,  the  greatest  damage  being  just  below 
the  middle.  Some  of  the  diagonal  braces  were  sagged,  having  been 
stretched  beyond  their  elastic  limit  (PI.  NLVI,  B).  In  the  southeast 
corner  of  the  third  story  the  bottom  and  top  loops  of  one  of  the  2-inch 
square  diagonals  were  pulled  apart,  and  several  of  the  rivets  in  the 
angle  connection  were  sheared  off ; in  the  southwest  corner  also  the 
top  diagonal  loop  pulled  apart,  the  diagonal  being  considerably  bent ; 
in  the  northwest  corner  seven  of  the  eight  f-inch  rivets  in  the  angle 
of  the  connection  for  the  diagonals  were  sheared  off  (PI.  XLVII,  B)  ; 
and  in  the  northeast  corner  all  but  2 inches  of  the  top  angle  was 
sheared,  and  the  north  diagonal  was  bent,  the  loop  having  been  pulled 
apart.  On  the  second  floor,  in  the  northeast  corner,  the  top  east 
diagonal  connection  pulled  away,  shearing  the  rivets;  in  the  south- 
east corner  the  top  angle  of  the  diagonal  connection  sheared  for 
about  2 inches,  and  four  of  the  1-inch  rivets  holding  the  cover  plate 
of  the  southwest  column  (PI.  XLVII,  A)  were  sheared,  as  were  also 


GENERAL  EARTHQUAKE  CONDITIONS  AND  EFFECTS. 


29 


two  of  the  rivets  holding  the  clip  support  for  the  west  girder.  The 
floor  of  the  main  building  consisted  of  groined  arches  of  stone  con- 
crete springing  from  concrete  piers  supported  by  cluster  piles.  The 
self-supporting  walls  of  sandstone  backed  with  brick  were  more  or 
less  shaken,  and  the  piers  of  the  driveways  were  badly  cracked ; the 
floors  were  of  stone  concrete  reenforced  with  expanded  metal  between 
I beams  and  supported  by  cast-iron  columns.  The  concrete  in  this 
building  appeared  to  be  undamaged. 

Most  of  the  entrances  to  the  cemeteries  were  wholly  or  partially 
wrecked,  and  the  burial  vaults  and  gravestones  were  all  more  or  less 
disarranged.  It  has  been  estimated  that  perhaps  60  per  cent  of  the 
monuments,  vaults,  etc.,  in  cemeteries  were  overturned  or  moved. 

In  Golden  Gate  Park  nearly  every  stone  or  brick  structure  was 
damaged.  The  emergency  hospital,  a single-story  brick  and  stone- 
veneered  building,  lost  its  gable  walls  and  was  damaged  in  the  same 
manner  as  other  structures  having  improperly  bonded  walls  laid  in 
lime  mortar,  and  deficient  in  proper  ties  between  the  masonry  and  the 
other  structural  parts.  The  gable  walls  of  the  restaurant  in  the 
children’s  playground  were  thrown  down  by  the  earthquake,  but 
the  greatest  damage  resulted  in  the  settling  of  the  foundation  of  one 
of  the  columns,  which  caused  the  collapse  of  the  structure.  The 
music  stand,  a stone-veneer  brick-backed  structure,  was  racked  and 
shaken.  Part  of  the  pediment  was  shaken  loose,  and  many  of  the 
columns  were  spalled  and  moved.  Some  of  the  walls  of  the  museum 
were  thrown  down,  and  its  contents  were  more  or  less  damaged. 
All  the  monuments  were  damaged.  The  Francis  Scott  Key  monu- 
ment (PI.  XX,  A)  was  racked  so  badly  that  the  arch  stones  were 
shaken  loose,  the  columns  spalled  at  cap  and  base,  and  the  monument 
as  a whole  moved  on  its  foundations. 

The  most  interesting  structure  in  Golden  Gate  Park  is  the  cyclo- 
rama  (PI.  XXIII,  A ),  on  the  top  of  Strawberry  Hill,  built  about 
fifteen  years  ago.  The  top  of  the  hill  had  been  leveled  off  in  order  to 
form  a foundation.  The  cyclorama  consisted  of  circular  walls  of 
reenforced  concrete,  the  aggregate  of  which  was  a hard  shale  crushed 
to  concrete  size.  This  material  was  very  inferior  and  yielded  a poor 
concrete.  The  reddish-brown  effect  was  obtained  by  means  of  a 
veneer  (hj  to  4 inches  thick)  of  a concrete  consisting  of  crushed  brick, 
sand,  and  cement.  The  reenforcement  in  the  base  consisted  of  four 
^-inch  cables  of  thirty  strands  each.  The  reenforcement  of  the 
columns  consisted  of  f-inch  twisted  bars  and  ^-inch  stirrups.  The 
entrance,  with  its  very  heavy,  massive  top,  should  have  been  of  hol- 
low-construction reenforced  concrete.  The  settling  of  the  foundation 
or  fill  under  the  vibration  of  the  earthquake  caused  the  structure  to 
collapse.  The  slip  (PI.  XXII,  B)  occurred  principally  on  the  north- 
east side,  the  movement  being  4 or  5 feet.  The  principal  crack  in 


30 


THE  SAN  ERANCISCO  EARTHQUAKE  AND  EIRE* 


the  base  was  about  11  inches  wide,  with  a half -inch  horizontal 
crack  leading  from  it  along  the  reenforcement.  The  floor  is  in  good 
condition,  except  the  pavement,  which  broke  into  blocks,  most  of  the 
planes  of  fracture  coinciding  with  the  actual  joints  between  the  dif- 
ferent sections.  Under  the  circumstances — the  undermining  of  the 
foundation  bj  the  slip  as  described — the  structure  developed  remark- 
able strength.  No  brick  or  stone  structure  could  have  stood  the  shock 
so  well.  The  rustic  railing  around  the  outside  of  the  walk  (PL 
XXII,  B ) , which  was  of  wrought-iron  pipe  covered  with  wire  mesh 
and  plastered  with  Portland-cement  mortar,  was  distorted  by  the  slip, 
but  otherwise  uninjured. 

At  the  bottom  of  Strawberry  Hill  is  a bridge  crossing  over  Stow 
Lake.  This  bridge  is  made  of  concrete,  and  showed  no  signs  of 
cracking,  although  the  banks  of  the  lake  slipped  into  the  water. 

BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 

GENERAL  STATEMENT. 

The  numerous  fires  that  broke  out  all  over  the  city  were  doubtless 
caused  by  the  collapse  of  chimneys  and  the  breaking  of  electric  con- 
nections. These  fires  were  at  first  confined  to  the  territory  south  of 
Market  street,  and  it  is  said  that  by  8 a.  m.  on  the  morning  of  April 
18  more  than  fifty  fires  were  recorded.  The  early  failure  of  the 
water  mains  rendered  the  city  helpless  and  placed  it  at  the  mercy  of 
the  flames,  the  fury  of  which  for  three  days  threatened  to  complete 
one  of  the  greatest  disasters  of  recent  years  and  to  obliterate  one  of 
the  most  beautiful  cities  in  the  country.  The  conflagration  was 
finally  checked,  at  the  barrier  presented  by  a wide  avenue,  by  a 
change  in  the  direction  of  the  wind  and  through  the  efforts  of  the 
fire  department,  using  water  pumped  from  the  bay  at  the  foot  of 
Van  Xess  avenue. 

San  Francisco  consisted  principally  of  frame  and  brick  structures, 
with  perhaps  forty  or  more  so-called  “ fireproofs,”  a few  buildings 
of  slow-burning  construction,  and  the  substantial  Government  build- 
ings. Many  of  the  buildings  contained  mercantile  stocks,  and  most 
of  them  were  exposed  to  exterior  fire  conditions  of  maximum  sever- 
ity. Since  every  type  of  construction  was  represented,  the  ruins 
afford  a most  excellent  opportunity  for  comparative  study,  although 
the  scope  of  the  information  obtained  is  incomplete,  as  a water  test 
is  lacking. 

In  comparing  the  behavior  of  the  various  structures  and  structural 
materials  it  has  been  thought  best  to  describe  the  condition  in  which 
certain  individual  buildings  were  left  by  the  earthquake  and  fire, 
and  to  present  the  salient  features  of  these  buildings  by  illustrations 
with  descriptive  legends.  The  following  descriptions,  which  for 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


31 


convenience  are  arranged  in  alphabetical  order,  cover  the  structures 
not  previously  mentioned  that  were  inspected  by  the  writer,  the 
total  number  embracing  nearly  every  building  that  was  left  stand- 
ing in  the  burned  district:  The  locations  of  these  buildings  can 

be  found  by  reference  to  the  map,  PL  LVI,  and  to  the  panorama, 
PL  LV. 

ACADEMY  OF  SCIENCES  BUILDING. 

The  Academy  of  Sciences  building,  819  Market  street,  views  of 
parts  of  which  are  shown  in  Pis.  XXIV,  A , and  XXV,  B , was  of 
ordinary  concrete  construction  and  six  stories  high,  and  was  com- 
pletely destroyed. 

A six-story  annex  having  brick  walls,  concrete-filled  cast-iron  col- 
umns, and  reenforced-concrete  floors,  was  connected  to  the  main 
building  on  the  rear.  The  brick  walls  of  the  annex  were  badly 
cracked  by  the  earthquake,  and  the  building  was  subsequently  com- 
pletely gutted  by  fire.  The  structure  itself  passed  through  a fairly 
hot  fire  successfully,  although  surrounded  by  buildings  which  were 
completely  wrecked.  Plaster  of  Paris  was  used  on  the  concrete-filled 
cast-iron  columns  and  seemed  to  stand  fire  much  better  than  lime  mor- 
tar. These  columns  are  shown  in  Pl.  XXV,  B , a view  taken  from 
the  third  floor  looking  southeast.  An  interesting  feature  of  the 
building  was  the  concrete-filled  cast-iron  column  that  supported  the 
south  wall.  Owing  to  the  unequal  expansion  of  the  cast  iron  and  the 
concrete  the  cast  iron  failed,  bulging  from  the  heat  and  cracking  on 
cooling,  as  shown  in  Pl.  XXIV,  A.  The  f-inch  or  1-inch  thickness 
of  concrete  which  covered  the  reenforcing  bars  proved  insufficient  in 
the  basement,  where  the  fire  was  fairly  hot.  The  heat  expanded  the 
bars,  thereby  ripping  off  the  concrete  layer  and  leaving  the  rods 
exposed. 

JETNA  (young,  OR  COMMISSARY ) BUILDING. 

The  five-story  HCtna  Building  (Pis.  XXIV,  B;  XXV,  A;  XXIX, 
Z>),  on  the  southwest  corner  of  Spear  and  Market  streets,  was  occu- 
pied by  the  Sellers  Brothers  Hardware  Company.  It  was  built  on 
piles  and  had  self-supporting  walls  of  gray  granite,  pressed  brick, 
and  terra  cotta.  The  steel  columns  and  girders  were  fireproofed  with 
expanded  metal,  plastered.  The  expanded-metal  reenforced-concrete 
floors  rested  upon  steel  girders  with  intermediate  ribs  of  concrete 
supported  by  5 -inch  by  ^-inch  bands  of  steel  without  fireproofing 
which  hooked  onto  the  top  flanges  of  the  girders. 

One  panel  of  the  fifth  floor,  which  was  rather  heavily  loaded  with 
tin  plate,  collapsed  because  of  the  expansion  of  the  above-mentioned 
steel  bands  from  the  heat,  which  was  sufficient  to  volatilize  the  tin 
even  from  the  middle  sheets  of  the  pile.  The  fall  of  the  load  of  tin 


32 


THE  SAlST  FRANCISCO  EARTHQUAKE  AND  FIRE. 

plate  caused  the  failure  of  the  third  floor,  as  shown  in  PI.  XXIX,  B. 
The  plaster  protection  of  the  columns  was  in  fair  condition,  and  the 
columns  were  uninjured.  The  principal  damage  from  earthquake 
was  to  the  brick  walls,  the  south  and  west  walls  showing  a number  of 
cracks.  The  granite  trimmings  around  the  doorway  and  the  terra- 
cotta trimmings  of  the  building  were  badly  spalled  by  the  fire,  as 
shown  in  PI.  XXIV,  B.  The  basement  floor,  which  was  of  concrete 
7 or  8 inches  thick,  was  pushed  up  under  the  sidewalk,  reducing  the 
headroom  at  this  point  from  8 feet  to  3J  feet,  approximately.  This 
bulging  was  probably  caused  by  settling  (PI.  XXV,  A ),  as  the 
foundation  piling  did  not  extend  under  the  sidewalk. 

appraisers’  warehouse  (united  states  custom-house). 

The  four-story  custom-house  building,  on  Jackson,  Washington, 
and  Battery  streets,  shown  in  PI.  XXVIII,  A , passed  through  both 
earthquake  and  fire  without  injury,  although  located  on  the  alluvial 
flats.  All  the  buildings  around  it  were  burned,  but  the  fire  did  not 
gain  a foothold  in  this  building,  and  there  was,  therefore,  no  fire  test. 
As  an  example  of  successful  resistance  of  the  earthquake  test,  how- 
ever, this  building  stands  as  a favorable  testimony  to  first-class  mate- 
rials and  workmanship.  The  walls  were  of  brick,  with  granite 
ornamentation,  and  the  roof  was  slate  covered.  The  partitions  and 
cross  walls  were  all  of  solid  brickwork,  and  the  only  damage  that  they 
sustained  consisted  of  a few  cracks  in  the  archways  near  the  stairways 
on  the  upper  floors. 

ARONSON  BUILDING. 

The  ten-story  Aronson  Building,  on  the  corner  of  Third  and  Mis- 
sion streets,  had  a steel  skeleton  with  hollow-tile  partitions  and  fire- 
proofing for  the  columns.  The  floors  were  of  concrete  reenforced 
with  expanded  metal. 

Two  of  the  columns  on  the  first  floor  buckled  by  reason  of  the  fail- 
ure of  the  hollow  tile  (PI.  XXVII,  B ),  the  columns  being  shortened 
about  10  inches.  Columns  also  buckled  in  the  basement  and  on  the 
fifth,  eighth,  and  tenth  floors.  In  the  basement  two  columns  were 
fireproofed  with  concrete,  and  remain  in  first-class  shape,  but  near 
them  are  two  badly  buckled  columns  which  were  fireproofed  with 
terra  cotta.  This  result  is  an  excellent  object  lesson  on  the  merits  of 
the  two  systems  of  fireproofing.  The  sandstone  was  badly  spalled  by 
fire,  and  the  walls  were  badly  racked  by  the  earthquake.  The  cast- 
iron  stairways  were  very  much  damaged.  The  fire  in  this  building 
was  not  severe. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


33 


BEKINS  VAN  AND  STORAGE  COMPANY’S  BUILDING. 

The  building  in  process  of  construction  by  the  Bekins  Van  and 
Storage  Company,  at  the  corner  of  Thirteenth  and  Mission  streets, 
was  the  only  example  of  the  pure  type  of  reenforced  concrete  in  the 
city  (PI.  XXVII,  A).  Two  of  the  six  floors  were  erected,  the  walls 
being  made  of  brick  laid  in  lime  mortar  and  the  floors  and  columns  of 
reenforced  concrete. 

The  walls  were  badly  cracked  by  the  earthquake,  but  the  reenforced 
concrete  was  not  injured.  Considerable  furniture  stored  in  the 
building  was  burned,  and  the  heat  slightly  blistered  the  under  surface 
of  the  concrete  floor,  which  was  still  green  at  the  time  of  the  disaster. 

BULLOCK  & JONES  BUILDING. 

The  Bullock  & Jones  Building,  on  Sutter  street  west  of  Mont- 
gomery street,  is  an  eight-story  steel  skeleton  with  floors  of  reenforced 
cinder  concrete,  hollow-tile  partitions  and  column  protection,  and 
bearing  walls  of  ornamental  terra  cotta  and  terra-cotta  pressed  brick. 
The  reenforced-concrete  floor  arches  were  haunched  between  steel 
girders,  but  were  not  continuous  over  the  girders. 

The  earthquake  damaged  the  outside  very  considerably.  The  build- 
ing is  of  rather  flimsy  construction,  and  it  is  a wonder  that  the  fire 
did  not  wreck  it.  The  terra  cotta  was  badly  spalled  by  the  fire, 
especially  around  the  windows,  and  the  hollow  tile  failed  badly,  both 
in  partitions  and  as  column  protection.  The  3-inch  terra-cotta  parti- 
tions failed  generally,  and  several  columns  buckled  on  the  third  and 
eighth  floors  (PI.  XXVI,  A).  The  elevator  inclosure,  which  was 
plastered  on  expanded  metal,  failed,  as  did  also  the  cast-iron  stair- 
ways. The  wood  covering  of  the  floors  and  the  wooden  nailing 
strips  were  burned.  The  concrete  floor  is  in  excellent  condition.  A 
few  panels  collapsed  where  the  steel  girders  were  displaced.  The 
distorted  unprotected  beams  and  girders  around  openings  show 
strikingly  the  folly  of  unprotected  steel  work. 

CALIFORNIA  CASKET  COMPANY’S  BUILDING. 

The  building  which  was  in  process  of  construction  on  Mission 
street  between  Fifth  and  Sixth  streets  by  the  California  Casket  Com- 
pany was  seven  stories  in  height  and  had  a steel  skeleton  and  floors  of 
reenforced  cinder  concrete.  The  self-supporting  walls  were  built  on 
the  sides  and  rear  of  brick  and  on  the  front  of  brick  faced  with 
sandstone,  which  was  spalled  by  the  heat,  although  there  was  no 
stock  and  little  combustible  material  in  the  building.  The  columns 


34 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


were  fireproofed  with  concrete.  The  brick  protection  around  many 
of  the  columns  was  jarred  loose,  and  the  brick  vaults  on  the  first,  sec- 
ond, and  third  floors  were  badly  cracked  around  the  archways  of  the 
openings  into  them,  as  shown  in  PI.  XXIX,  A,  a view  of  a vault  in 
the  second  story.  The  stairways  were  constructed  of  concrete  with 
steel  channel  horses  and  were  cracked  in  a number  of  places,  espe- 
cially at  the  landings.  Some  of  the  wooden  window  frames  were 
burned,  but  the  fire  was  not  very  severe  either  in  the  building  or  sur- 
rounding it,  the  greatest  damage  resulting  from  the  earthquake. 
The  partitions  inclosing  stairways  and  elevator  shafts  were  of  the 
usual  flimsy  metal  lath  and  plaster  type.  The  walls  were  so  badly 
cracked  as  to  require  partial  rebuilding,  especially  at  the  southwest 
and  northwest  corners. 

CALL  ( CLAUS  SPRECKELSl  BUILDING. 

The  Call  Building  (fifteen  stories  besides  the  dome),  corner  of 
Third  and  Market  streets,  was  one  of  the  best-designed  skeleton  build- 
ings in  San  Francisco.  It  was  fairly  well  braced  laterally,  and  the 
workmanship  was  first  class.  It  stood  the  earthquake  shock  well  be- 
cause of  its  excellent  foundation,  which  extended  25  feet  below  the  side- 
walk and  consisted  of  a grillage  of  steel  beams  embedded  in  concrete. 
The  main  defect  was  in  the  fireproofing  of  the  floors  and  columns, 
in  which  terra  cotta  was  used,  and  the  greatest  damage  to  the  build- 
ing was  from  fire.  Although  some  of  the  diagonal  braces  were  bent 
and  had  apparently  been  stretched  so  as  to  take  a permanent  set,  the 
general  behavior  of  the  structure  demonstrates  that  high  build- 
ings subject  to  earthquake  can  be  erected  with  safety  even  on  sand 
foundations. 

The  floors  were  of  reenforced  concrete  up  to  the  seventh  story  and 
of  hollow-tile  arches  above,  topped  with  cinder  concrete.  The  par- 
titions were  principally  3-inch  hollow  tile,  and  these  failed  very  gen- 
erally. The  terra-cotta  fireproofing  around  the  columns  proved  inef- 
fective, and  although  the  steel  did  not  buckle,  the  paint  had  been 
burned  off  the  metal.  Wood  floors  laid  on  wood  nailing  strips  were 
used  in  all  offices  and  were  all  destroyed  by  fire..  The  marble  tiling 
and  wainscoting  of  the  corridors  was  either  shaken  down  by  the 
earthquake  or  destroyed  by  the  fire.  The  stairways  had  cast-iron 
horses  and  marble  treads,  most  of  the  latter  being  calcined.  The 
suspended  wire  lath  and  plaster  ceilings  were  generally  destroyed 
because  of  the  lack  of  proper  fastenings.  The  curtain  walls  of 
granite  and  sandstone  were  not  damaged  by  the  earthquake,  but  were 
considerably  spalled  by  the  fire. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


35 


CHRONICLE  BUILDINGS. 

The  Chronicle  buildings,  corner  of  Market  and  Kearney  streets, 
comprised  an  old  ten-story  structure  and  a new  fifteen-story  annex 
that  was  in  process  of  construction,  both  shown  in  PL  XXX,  B.  The 
old  building  consisted  of  steel  beams  and  protected  cast-iron  columns, 
with  self-supporting  walls,  which  had  a brownstone  front  up  to  the 
second  story  and  were  ornamented  with  terra  cotta  above.  The 
floor  was  of  hollow  tile,  filled  with  cinder  concrete  and  covered  with 
wood.  The  cast-iron  columns  were  fireproofed  with  3-inch  hollow 
tile,  and  4-inch  hollow  tile  was  used  for  the  partitions.  The  terra- 
cotta partitions  and  fireproofing  entirely  collapsed.  The  building 
appeared  to  have  stood  the  earthquake  shock,  and  received  its  prin- 
cipal damage  through  the  fire.  The  collapse  of  the  western  section 
of  the  building  was  probably  due  to  the  buckling  of  the  cast-iron 
columns. 

In  the  annex  terra-cotta  hollow  tile  was  used  for  the  floor  con- 
struction, 4-inch  hollow  tile  for  the  partitions,  and  3-inch  hollow 
tile  for  fireproofing  the  columns  and  girders.  The  curtain  walls 
were  built  of  sandstone,  with  terra-cotta  trimmings  for  the  front 
walls  of  the  first  and  second  stories,  and  brick  and  terra  cotta  for 
the  remainder.  The  building  was  racked  considerably  by  the  earth- 
quake, the  front  walls  developing  the  characteristic  X cracks  (a 
number  of  which  may  be  perceived  by  a close  inspection  of  PI. 
XXX,  B ),  due  to  a lack  of  diagonal  bracing  of  the  steel  skeleton. 
The  tiling  failed  extensively,  the  lower  webs  spalling  off  and  the 
columns  buckling  in  the  southwest  corner  on  the  upper  floors  above 
the  roof  of  the  old  Chronicle  Building.  There  was  little  combustible 
material  in  the  building,  and  the  trim  had  not  started;  a few  of  the 
wooden  window  frames  only  burned;  so  that  the  fire  test  was  not 
great. 

CITY  HALL  AND  HALL  OF  RECORDS. 

The  city  hall  (PI.  XXXI)  was  a brick  building,  at  City  Hall 
avenue,  Larkin  street,  and  McAllister  street,  consisting  of  steel  floor 
beams  and  corrugated-iron  arches  with  cinder-concrete  filling.  It 
was  wrecked  by  the  earthquake  and  subsequently  gutted  by  the  fire. 
A prominent  feature  was  a central  tower,  surmounted  by  a dome 
built  over  a structural  steel  skeleton.  Grouped  around  the  dome 
were  a number  of  cast-iron  columns  of  half-inch  metal  filled  with 
brick  concrete  supported  on  brackets.  Some  of  these  columns  in 
falling  broke  into  small  pieces.  The  brickwork  was  completely 
shaken  from  the  central  tower.  The  cement-plastered  brick  walls 
were  laid  in  lime  mortar  of  generally  poor  quality  and  without 
adequate  tie  to  the  steel  work.  In  some  places  there  was  an  absence 


36 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


of  any  mortar,  but  in  others  it  was  very  good,  the  brick  walls  falling 
in  large  masses  and  the  broken  bricks  showing  the  mortar  to  have 
been  the  stronger.  The  massive  architectural  ornamentations  were 
top-heavy  and  lacked  adequate  bracing.  The  ceiling  was  formed  of 
corrugated  metal  against  which  the  mortar  plaster  was  pressed,  with 
intermediate  brick  partitions  where  the  span  of  the  beams  was  too 
great.  The  expansion  of  the  corrugated-iron  arches  by  the  heat 
produced  a rise  at  the  crown,  and  the  softening  of  the  iron  caused 
the  arches  to  fail ; they  would  have  been  much  stronger  without  the 
unprotected  corrugated  iron.  In  the  treasury  department  a granite 
column  was  badly  spalled  by  the  fire.  The  building  was  a monu- 
ment of  bad  design  and  poor  materials  and  workmanship,  and  was 
not,  therefore,  of  such  a character  that  it  could  be  expected  to 
resist  successfully  the  effect  of  earthquake  or  fire. 

The  damage  done  to  the  hall  of  records  by  the  earthquake  was  not 
serious,  and  consisted  of  the  falling  of  a small  section  of  brickwork 
from  the  third  story  on  the  west  side  and  other  cracks  in  the  walls. 
The  fire,  however,  destroyed  the  contents  of  the  building,  leaving  only 
the  shell  standing. 

CROCKER  BUILDING. 

The  ten-story  Crocker  Building,  corner  of  Powell  and  Market 
streets,  was  a steel-skeleton  structure,  with  hollow-tile  floor  arches, 
partitions,  and  fireproofing  for  columns  and  girders.  The  first  two 
stories  of  the  self-supporting  walls  were  granite,  and  the  remainder 
buff  brick  with  terra  cotta. 

On  the  ninth  and  tenth  floors  the  light  Phoenix  columns  buckled 
through  the  failure  of  the  hollow-tile  fireproofing.  The  fire  was  only 
moderate,  however,  and  except  on  the  ninth  and  tenth  floors  the 
steel  appeared  to  be  in  good  condition.  The  weakness  of  hollow  floor 
tiles  for  carrying  heavy  loads  was  demonstrated  in  a number  of 
places  where  the  tile  floors  had  been  broken  by  the  fall  of  safes. 
The  lower  webs  of  the  floor  tiles  had  failed  over  extensive  areas. 
The  stairways,  with  their  cast-iron  horses  and  slate  treads,  were  not 
damaged  to  any  great  Extent.  The  floors  were  topped  with  cinder 
concrete  and  covered  with  wood  in  the  offices  and  with  mosaic  in 
the  corridors. 

EMPORIUM. 

In  the  building  known  as  the  “ Emporium,”  825-855  Market 
street,  west  of  the  Academy  of  Sciences,  the  first  two  stories  were 
fireproofed  with  terra  cotta.  Slow-burning  wooden  construction 
was  used  above  the  second  floor.  As  shown  in  PI.  XXXII,  very 
little  of  this  structure  save  the  exterior  walls  was  left  standing. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


37 


FAIRMOUNT  HOTEL. 

The  six-story  Fairmount  Hotel,  California,  Mason,  Powell,  and 
Sacramento  streets,  was  nearly  completed,  and  the  only  combustible 
in  it  was  the  lumber  used  in  construction.  It  consisted  of  a steel 
skeleton  with  floors  of  cinder  concrete  reenforced  with  expanded 
metal.  The  walls  were  self-supporting  and  were  constructed  of 
granite  backed  with  brick  up  to  the  third  floor  and  of  light-colored 
terra  cotta  in  the  upper  stories.  The  ceilings  were  of  the  suspended 
type  plastered  on  metal  lath.  The  original  plans  called  for  the 
columns  to  be  fireproofed  with  concrete,  but  because  of  the  greater 
expense  of  this  material  the  plans  were  changed  and  the  expanded 
metal  and  plaster  partitions  were  molded  around  these  columns.  The 
result  was  that  even  under  the  moderate  heat  to  which  the  building 
was  subjected  about  40  of  the  columns  buckled,  including  23  on  the 
third  floor  alone  (PI.  XXXIV),  and  the  partitions  were  completely 
wrecked.  The  effect  of  the  earthquake  shock  was  principally  con- 
fined to  the  west  end  of  the  north  front.  The  terra  cotta  was  spalled 
considerably  and  the  granite  only  slightly  by  fire.  The  exterior  dam- 
age was  not  very  great. 

JAMES  FLOOD  BUILDING. 


The  steel-frame  twelve-story  James  Flood  Building,  on  the  north- 
east corner  of  Powell  and  Market  streets,  was  constructed  with  seg- 
mental hollow-tile  floor  arches  topped  with  cinder  concrete  and  sus- 
pended ceilings  plastered  on  metal  lath.  The  columns  were  con- 
structed of  Z bars  and  were  filled  with  common  brick  to  the  outer 
edge  of  the  section  and  the  whole  inclosed  with  3-inch  hollow  tile. 
This  tile  failed  (PI.  XXXV,  X),  although  the  fire  could  not  have 
been  very  severe,  for  the  wooden  floor  in  the  offices  was  only  partly 
burned  and  there  were  a number  of  wardrobes  and  switch  boxes  of 
wood,  besides  the  door  and  window  frames  and  wainscoting,  which 
were  not  burned.  The  stairways,  which  had  cast-iron  horses  and 
marble  treads,  were  in  fair  condition.  The  corridors  were  tiled  with 
marble.  The  stonework  was  very  slightly  spalled  by  fire,  and  the 
principal  damage  by  earthquake  was  a cracking  of  the  sandstone  at 
several  of  the  entrances  (PI.  XXXIII,  B ). 

GRANT  BUILDING. 


The  lower  floor  of  the  Grant  Building,  at  the  southeast  corner  of 
Seventh  and  Market  streets,  was  used  for  a bank,  the  upper  floors  for 
offices.  It  was  eight  stories  high  and  had  a steel  frame  with  cinder- 
concrete  floors,  the  beams  and  girders  being  of  solid  concrete.  The 
first  story  had  self-supporting  walls  of  sandstone,  and  the  remaining 


7171— Bull.  324-07- 


4 


38 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


stories  walls  of  pressed  terra-cotta  brick,  trimmed  with  sandstone. 
Hollow  tile  was  used  to  fireproof  the  columns  and  for  the  partitions. 

The  cast-iron  stairways  with  marble  treads  were  damaged  but 
slightly.  The  hollow-tile  partitions  were  badly  wrecked,  most  of 
them  being  thrown  down.  The  building  was  injured  considerably 
by  dynamiting,  which  partly  disguised  the  damage  caused  by  the 
earthquake. 

HOTEL  HAMILTON. 

The  twelve-story  apartment  house  known  as  the  Hotel  Hamilton,  on 
the  north  side  of  Ellis  street  between  Mason  and  Powell  streets,  was 
a steel-skeleton  structure  with  floors  of  reenforced  concrete  and  gird- 
ers and  beams  of  solid  concrete.  Plastered  wire  lath  served  as  a 
fireproofing  for  the  columns,  and  the  suspended  ceilings  were  of  the 
same  material.  This  construction  may  be  seen  in  PL  XXXVI,  B. 
Four-inch  hollow  tile  was  used  in  the  partitions. 

The  marble  treads  of  the  cast-iron  stairway  were  to  a large  extent 
calcined.  A number  of  the  columns  buckled  on  the  first,  sixth,  and 
seventh  floors,  the  wire  lath  being  entirely  insufficient.  This  buckling 
caused  the  floors  throughout  the  building  to  settle.  The  damage  by 
earthquake  to  the  curtain  walls  was  slight.  The  sandstone  finish  of 
the  first  four  floors  spalled  but  little  from  the  heat;  the  terra  cotta 
above,  however,  was  considerably  spalled. 

HIBERNIA  SAVINGS  AND  LOAN  SOCIETY’S  BUILDING. 

The  two-story  bank  building  of  the  Hibernia  Savings  and  Loan 
Society,  on  the  northwest  corner  of  McAllister  and  Jones  streets  (PI. 
XXXVII,  A ) , was  constructed  with  two  street  fronts  of  granite  and 
rear  walls  of  brick.  The  gallery  and  a portion  of  the  second  floor 
were  constructed  of  brick  and  concrete  arches.  The  ceilings  and 
ornamental  work  were  plastered  wire  lath.  The  dome  was  sheathed 
with  copper.  The  granite  fronts,  especially  around  the  doors  and 
windows,  were  badly  spalled  by  fire;  other  damage  to  the  structure 
was  confined  almost  entirely  to  the  roof. 

HOBART  BUILDING. 

The  five-story  Hobart  Building,  on  the  north  side  of  Market  street 
near  Post  street,  had  bearing  walls  of  brick  faced  with  granite  up  to 
the  second  story  and  of  brick  trimmed  with  terra  cotta  for  the  remain- 
ing stories.  The  framework  consisted  of  cast-iron  columns  with  steel 
girders  and  beams;  the  floors  of  segmental  arches  of  plain  concrete. 
The  cast-iron  columns  were  fireproofed  with  brick  in  the  basement, 
and  with  wire  lath  and  plaster  on  the  first  floor.  The  partitions  were 
of  4-inch  hollow  tile.  The  ceilings  were  plastered  wire  lath  attached 
to  the  lower  flanges  of  the  beams. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


39 


The  granite  columns  were  spalled  practically  to  destruction  by  fire, 
as  shown  in  PI.  XXXVI,  A.  The  fire  in  one  section  appeared  to  be 
very  hot  and  caused  a collapse  of  one  of  the  floors,  which  was  followed 
by  the  failure  of  the  other  floors  of  that  section  of  the  building. 

JACKSON  BREWING  COMPANY’S  BUILDING. 

The  plant  of  the  Jackson  Brewing  Company,  on  the  southeast 
corner  of  Eleventh  and  Folsom  streets  (PL  XXXVII,  B ),  was  in 
process  of  construction  and  was  wrecked  by  the  earthquake,  the 
damage  by  fire  being  but  slight.  The  brick  walls  were  laid  in  lime 
mortar  of  poor  quality.  The  steel  beams  and  girders  were  supported 
by  cast-iron  columns.  Many  of  the  various  steel  members  were 
bolted  together  with  an  insufficient  number  of  bolts,  the  girders 
and  beams  resting  upon  the  walls  without  any  tie;  the  columns, 
girders,  and  beams  were  not  fireproofed,  and  in  the  eastern  half  the 
concrete  floor  slabs,  6 inches  thick,  were  without  reenforcement.  Sev- 
eral persons  were  killed  by  the  collapse  of  the  tower.  That  this  build- 
ing should  have  been  wrecked  is  not  surprising,  as  the  design  was  bad 
and  the  material  and  workmanship  were  very  poor. 

HALL  OF  JUSTICE. 

A steel  frame  and  floors  of  cinder  concrete  reenforced  with  ex- 
panded metal  were  used  in  the  Hall  of  Justice,  at  the  corner  of 
Kearney  and  Washington  streets.  The  earthquake  largely  wrecked 
this  building  (PI.  XXXIX,  A).  The  cupola  of  light  steel  angles 
collapsed  from  the  heat  after  being  racked  by  the  earthquake.  The 
walls  were  laid  in  lime  mortar,  and  the  floor  panels  were  stiffened, 
as  in  the  iEtna  Building,  with  5 by  -J  inch  steel  bands.  The  floors 
were  wood  covered  and  were  burned.  The  suspended  ceilings  were 
of  plastered  expanded  metal  lath,  the  partitions  of  3-inch  expanded 
metal,  plastered,  while  the  columns  had  a double  layer  of  plastered 
expanded  metal  with  a lj-inch  dead  air  space  between.  The  sus- 
pended ceilings  failed,  as  shown  in  PI.  XXXV,  Z?,  a view  taken  on 
the  second  floor.  One  of  the  central  basement  columns  buckled 
and  collapsed  18  inches,  presenting  the  appearance  of  having  punched 
a hole  in  the  floor.  Two  of  the  six-cell  prison  cages  fell  through 
the  floors  into  the  basement.  The  cast-iron  stairways  with  marble 
treads  are  in  fair  shape. 

KAMM  BUILDING. 

The  seven-story  L-shaped  Kamm  Building,  on  Market  street,  west  of 
the  Call  Building  and  adjacent  to  it  on  two  sides,  had  a steel  skeleton 
and  self-supporting  sandstone  walls.  The  floors  were  of  reenforced 
stone  concrete,  covered  with  wood,  with  hollow  partitions  and  sus- 


40 


THE.  SAN  FEAN  CISCO  EAKTHQXJAKE  AND  FLEE. 


pended  ceilings  of  plastered  wire  lath,  the  steel  columns,  beams,  and 
girders  being  also  fireproofed  with  plastered  wire  lath. 

The  rear  structure  collapsed  when  a number  of  columns  in  the  base- 
ment buckled 'under  the  intense  heat  produced  by  the  burning  wall 
paper,  of  which  there  was  a large  quantity  stored  in  the  basement. 

KOHL  (HAYWARD)  BUILDING. 

The  Kohl  Building,  on  the  northeast  corner  of  California  and  Mont- 
gomery streets,  which  presented  a number  of  interesting  features,  is 
of  a modern  type  of  steel-skeleton  construction,  11  stories  in  height. 
The  floors  were  of  concrete,  reenforced  with  expanded  metal,  and  the 
columns  were  incased  with  expanded  metal,  plastered.  The  partitions 
were  made  of  hollow  tile,  with  metal-covered  frames,  doors,  and 
windows.  The  suspended  ceilings  were  of  plastered  expanded  metal. 

The  earthquake  did  but  little  damage,  breaking  a few  panes  of  glass 
and  loosening  the  marble  wainscoting.  There  were  also  a few  cracks 
in  the  stone  facing  at  the  southwest  corner  of  the  first  floor.  The 
first,  second,  third,  fourth,  and  part  of  the  seventh  floors  were  burned, 
the  remainder  of  the  building  being  undamaged.  The  structure  was 
surrounded  by  a series  of  rather  low  buildings,  and  the  fire  was  not 
severe  either  on  the  outside  or  inside.  The  character  of  the  inside 
trim  prevented  to  a considerable  degree  the  spread  of  the  flames. 
One  defect  in  the  construction  wTas  in  the  use  of  plate  glass  instead  of 
wire  .glass  for  the  doors  and  windows. 


MAJESTIC  THEATER. 

The  Majestic  Theater,  at  the  corner  of  Ninth  and  Market  streets 
(PI.  XXXIX,  B ),  although  one  of  the  largest  and  best  of  the  San 
F rancisco  theaters,  was  particularly  bad  in  design.  The  roof  trusses, 
of  about  80-foot  span  and  perhaps  75  feet  above  the  ground,  were 
carried  on  18-inch  walls  insufficiently  reenforced  by  pilasters. 

The  common  brick  bearing  walls  were  completely  wrecked  by  the 
earthquake.  The  roof  trusses  over  the  stage  collapsed.  The  walls 
still  show  extensive  earthquake  cracks,  as  will  be  seen  from  the  illus- 
tration. The  building  was  subsequently  gutted  by  fire. 

MERCANTILE  TRUST  COMPANY’S  BUILDING. 

The  three-story  Mercantile  Trust  Company’s  building,  on  Califor- 
nia street  east  of  the  Kohl  Building,  like  most  of  the  low  structures, 
appeared  to  be  immune  from  the  earthquake  and  fire.  The  principal 
damage  was  caused  by  the  falling  walls  of  adjacent  buildings,  which 
smashed  in  the  steel  roof  with  its  heavy  glass  and  started  a fire  in 
the  interior.  The  granite  facing  around  the  windows  spalled  to  a 
slight  extent,  but  the  building  was  not  badly  damaged. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


41 


merchants’  exchange  building. 

The  recently  constructed  modern  office  building  known  as  the 
Merchants’  Exchange,  on  California  street  between  Montgomery  and 
Sansome  streets,  caught  fire  from  the  outside  and  its  contents  were 
destroyed.  The  edifice  was  13  stories  in  height,  with  steel  skeleton, 
fireproofed  with  plastered  wire  lath  and  reenforced-concrete  floors. 
The  floors  of  the  rooms  were  of  wood ; the  corridors  were  floored  and 
wainscoted  with  marble.  The  fireproofing  of  the  columns  consisted 
of  two  layers  of  quarter-inch  wire  lath  with  a dead  air  space  between, 
except  those  which  were  bricked  into  the  outside  walls.  The  sus- 
pended ceilings  and  partitions  were  likewise  of  plastered  wire  lath, 
and  the  same  material  formed  the  walls  of  the  u fireproof  ” vaults. 
The  curtain  walls  were  of  brick  on  the  sides  and  rear;  on  the  front 
the  first  two  stories  were  of  granite,  the  remainder  being  pressed 
terra  cotta  with  terra-cotta  trimmings.  The  heat  of  the  fire  was 
sufficient  to  calcine  a large  portion  of  the  wainscoting  and  the  marble 
treads  of  the  cast-iron  stairways.  Though  not  completely  destroy- 
ing it,  the  fire  burned  the  life  out  of  the  plaster,  all  of  which  will 
have  to  be  renewed.  The  rear  walls  were  cracked  by  the  earthquake. 
The  enameled  brickwork  of  the  light  well  (PL  XL,  A)  ^xlso  shows 
earthquake  cracks,  and  is  badly  spalled  by  the.  fire.  The  stonework 
was  slightly  spalled  by  the  heat.  The  metal  frames  between  the 
windows  opening  into  the  court  were  buckled,  the  cinder-concrete 
fireproofing  being  insufficient.  The  terra-cotta  trim  in  the  light  well 
was  also  badly  spalled. 

MILLS  BUILDING. 

The  eleven-story  Mills  Building,  at  the  northeast  corner  of  Bush 
and  Montgomery  streets,  had  a steel  skeleton  with  hollow-tile  fire- 
proofing and  hollow-tile  partitions.  The  floors  were  also  of  hollow 
tile  topped  with  cinder  concrete  and  covered  with  wood  in  the  offices ; 
the  tiling  and  wainscoting  of  the  corridors  were  of  marble. 

The  Avails  were  racked  by  the  earthquake.  The  hollow  tile  failed 
and  left  the  steel  skeleton  exposed  to  the  fire.  Just  how  seriously 
it  was  damaged  is  problematical;  four  of  the  basement  columns 
buckled  (PI.  XL,  B ),  the  lower  webs  of  the  floor  tiles  failed  over 
large  areas  (PI.  XLY,  B) , and  the  partitions  and  the  marble  treads 
of  the  cast-iron  stairways  were  destroyed.  In  the  light  well  the 
Avindow  casings  were  distorted  by  heat  because  of  insufficient  fire- 
proofing, and  the  terra  cotta,  granite,  and  exterior  trim  of  the  Avail 
Avere  badly  spalled.  Owing  to  the  failure  of  the  floor  tile  many 
safes  fell  through  the  several  floors.  The  building  should  be  rebuilt. 


42 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  EIRE. 


UNITED  STATES  MINT. 

The  massive  three-story  Government  building  occupied  by  the 
United  States  mint,  at  Fifth  and  Mission  streets  (PI.  XXXVIII), 
which  was  not  damaged  to  any  appreciable  extent  by  the  earthquake, 
was  inspected  in  company  with  the  superintendent,  Mr.  Leach.  One 
of  the  interior  walls  was  weakened  by  a break  in  the  sewer  which  ran 
under  it,  and  one  of  the  chimneys  was  cracked  at  the  top.  This  struc- 
ture, which  is  located  at  the  intersection  of  two  wide  streets,  is  built 
on  soft  alluvium,  but  rests  upon  a substantial  pile  foundation.  The 
bearing  walls  were  of  solid  brick  faced  with  granite,  the  northwest 
face  of  which  was  badly  spalled  by  fire  (PI.  XXXVIII,  B ).  The 
floors  consisted  of  brick  arches  between  steel  beams,  finished  in  cement. 
They  were  supported  by  cast-iron  columns,  which  were  unprotected 
except  where  they  were  incased  by  the  heavy  brick  wall  partitions. 
The  doors  and  windows  Avere  of  wood  glazed  with  plate  glass,  the 
windows  on  the  first  and  second  floors  being  fitted  with  folding  inside 
iron  shutters.  The  roof  and  northwest  side  of  the  third  story  caught 
fire  from  without,  but  as  an  artesian  well  provided  an  independent 
supply  of  water  the  fire  was  prevented  from  gaining  a foothold,  and 
the  building  was  but  slightly  damaged. 

MONADNOCK  BUILDING. 

The  ten-story  Monadnock  office  building,  on  the  south  side  of 
Market  street  between  the  Palace  Hotel  and  the  Call  Building,  was 
in  process  of  construction  and  Avas  damaged  by  the  earthquake  and 
by  dynamiting  in  the  vicinity,  besides  being  gutted  by  fire. 

The  west  wall  was  not  erected,  as  that  section  Avas  incomplete,  pend- 
ing the  satisfactory  purchase  of  the  land.  The  structure  had  a steel 
skeleton  frame,  reenforced-concrete  floors,  with  a ceiling  of  plastered 
expanded  metal.  The  columns  Avere  incased  Avith  two  layers  of  plas- 
tered expanded  metal,  with  a dead  air  space  between  them.  The 
partitions  were  3 inches  thick,  plastered  on  wire  lath.  The  floors  were 
topped  with  cinder  concrete  and  covered  with  tile  in  the  corridors 
and  with  wood  in  the  offices.  The  corridors  were  to  have  been  wain- 
scoted with  marble  also.  The  building  Avas  not  adequately  braced 
diagonally.  Large  areas  of  the  exterior  were  damaged  and  Avill 
have  to  come  down.  Two  unprotected  columns  in  the  basement  col- 
lapsed, settling  the  floors  for  7 inches.  The  building  is  to  be  repaired 
by  jacking  up  the  floors  and  replacing  the  buckled  columns.  What 
effect  this  will  have  on  the  reenforced-concrete  floors  is  problematical. 
Certainly  their  factor  of  safety  is  reduced,  and  in  the  judgment  of 
the  writer  the  building  is  materially  weakened,  for  the  reason  that 
the  buckling  of  the  columns,  which  resulted  in  the  settling  of  the 
floor,  cracked  the  floor  beams  at  their  points  of  connection  with  the 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


43 


columns.  While  the  jacking  up  closes  the  cracks,  it  can  not  restore 
the  original  strength  of  the  connection,  which  although  not  entirely 
gone  has  been  reduced  to  a very  small  percentage  of  its  former  value. 

MURPHY  BUILDING. 

The  columns  of  the  five-story  Murphy  Building,  at  the  corner  of 
Kearney  and  California  streets,  were  constructed  of  corner  angles 
latticed  and  filled  with  cinder  concrete,  the  whole  being  incased  with 
plastered  metal  lath,  with  a dead  air  space  between.  The  floors 
consisted  of  cinder-concrete  arches  between  channels. 

This  building  was  completely  gutted  by  the  fire,  although  the 
structure  itself  was  left  in  fair  condition.  The  metal-lath  ceilings 
and  partitions  stood  the  test  fairly  well,  though  some  of  the  parti- 
tions were  buckled  out  of  shape.  A view  of  this  damage  on  the  third 
floor  is  shown  in  PL  XLI,  B.  The  terra-cotta  trimmings  and  the 
copper  work  around  the  bay  windows  were  badly  damaged  by  fire. 

MUTUAL  LIFE  BUILDING. 

The  nine-story  Mutual  Life  Building,  at  the  southeast  corner  of 
Sansome  and  California  streets,  was  fireproofed  throughout  with 
terra-cotta  hollow  tile,  with  hollow-tile  partitions.  The  treads  of 
the  cast-iron  stairways  and  the  wainscoting  and  tile  of  the  corridors 
were  of  marble.  The  office  floors  were  constructed  of  cinder  con- 
crete covered  with  wood. 

The  damage  to  this  building  from  the  earthquake  was  very  slight. 
The  fire  in  the  building,  while  not  severe,  was  sufficient  to  cause  the 
failure  of  the  tile  fireproofing  of  the  roof  trusses,  which  collapsed 
from  exposure  to  heat  (PL  XLII,  A). 

PACIFIC  STATES  TELEPHONE  AND  TELEGRAPH  COMPANY’S  BUILDING. 

The  recently  completed  eight-story  building  of  the  Pacific  States 
Telephone  and  Telegraph  Company,  on  Bush  street  between  Grant 
and  Kearney  streets  (Pl.  XLI,  A),  embodied  many  good  and  a few 
bad  features  of  construction.  The  side  and  rear  walls  were  of  brick, 
and  the  front  was  of  terra-cotta  pressed  brick  and  terra-cotta  trim- 
mings. All  the  walls  were  self-supporting.  The  floors  were  of  reen- 
forced concrete  between  steel  beams,  and  the  ceilings  for  all  floors 
above  the  basement  were  suspended  metal  lath,  plastered. 

The  walls  were  cracked  somewhat  by  the  earthquake,  and  the 
pilasters  on  the  exterior  were  spalled.  The  girders  and  columns 
supporting  the  floors  were  fireproofed  with  concrete  and  were  in 
excellent  shape  after  the  fire.  The  window  protection  was  excel- 
lent: the  front  was  provided  with  Kinnear  rolling  shutters,  with 
plate-glass  metal-covered  windows,  while  the  side  windows  had 


44 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


metal-covered  sash  and  frames,  with  wire  glass,  and  tin-covered 
sliding  shutters.  The  earthquake  racked  the  front  sufficiently  to 
prevent  the  shutters  from  working.  The  heat  produced  by  the  burn- 
ing insulated  wire  and  other  supplies  was  high  and  protracted.  The 
reenforced-concrete  beams  of  the  roof  were  weakened  by  heat  and 
will  have  to  be  replaced.  The  concrete  in  general,  however,  stood 
this  trial  exceedingly  well  in  view  of  the  protracted  high  tempera- 
ture. The  fire  caught  through  an  unprotected  rear  door  in  the  south- 
west corner,  and  the  break  in  the  roof  made  possible  a very  hot  fire, 
which  melted  glass  and  even  welded  nails.  The  concrete  floors  and 
the  column  protection  were  not  damaged  in  the  slightest.  If  the 
methods  of  fire  protection  had  been  consistent  throughout,  it  is  prob- 
able that  this  building  would  have  escaped  without  damage. 

POST-OFFICE  BUILDING. 

The  writer  made  a thorough  examination  of  the  post-office  build- 
ing, on  Mission  street  between  Sixth  and  Seventh  streets,  in  company 
with  J.  W.  Roberts,  superintendent  of  construction,  of  the  Supervis- 
ing Architect’s  Office.  This  three-story  structure  rested  on  a founda- 
tion consisting  of  steel  beams  incased  in  concrete,  carried  through  the 
soft  alluviunqto  a hard  gravel,  the  depth  varying  from  30  feet  at 
Seventh  and  Mission  streets  to  12  and  14  feet  at  the  opposite  corner. 
The  building  had  a steel  frame,  expanded-metal  and  concrete  floors, 
and  plastered  expanded-metal  suspended  ceilings.  All  partitions  or 
interior  walls  were  of  terra-cotta  hollow  tile,  laid  with  full  joints  of 
Portland-cement  mortar,  the  terra-cotta  work  being  first  class  in  every 
particular.  The  corridors  were  tiled  and  wainscoted  with  marble. 
The  exterior  walls  were  of  granite  and  were  thoroughly  anchored, 
each  stone  being  fastened  to  the  steel  work  and  doweled  and  pinned 
to  the  adjacent  stones.  The  outer  facing  of  granite  is  carried  on  the 
steel  work  and  is  not  backed  with  brick,  there  being  an  inner  wall  of 
terra  cotta,  with  a dead  air  space  between,  which  serves  as  a passage- 
way for  pipes,  flues,  etc. 

The  ground  at  the  corner  of  Seventh  and  Mission  streets  settled 
about  5 feet  (PI.  XLIII,  B).  The  floor  of  the  building  was  slightly 
cracked  at  that  point,  and  Mr.  Roberts  stated  that  there  was  a set- 
tling of  about  If  inches.  The  outer  walls  were  considerably  racked 
(Pis.  XLIII,  A;  XLIY)  by  the  earthquake,  many  stones  having 
been  shaken  entirely  loose  from  the  steel  work  in  some  places,  while 
in  others  a number  of  stones  were  started  from  their  beds,  and  the 
anchorage  was  broken.  There  were  also  many  cracks,  especially  in 
some  of  the  exterior  pilasters,  which  were  formed  of  two  steel  col- 
umns, 12  feet  apart,  without  diagonal  bracing,  the  hollow  space  being 
used  for  heating  and  ventilating  apparatus.  These  pilasters  were 
badly  racked. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


45 


The  worst  damage  appeared  to  be  in  the  interior  walls  of  hollow 
tile,  which  were  very  extensively  cracked,  especially  on  the  first 
and  second  floors.  The  plaster  finish  on  the  hollow-tile  partitions 
strengthened  them  very  considerably.  One  portion  of  the  mosaic 
ceilings  of  the  corridors  on  the  main  floor  was  laid  in  Portland- 
cement  mortar  on  a flat  tiled  arch  and  was  badly  cracked;  another 
portion,  laid  in  Portland  cement  against  wire  lath  plastered,  was 
undamaged.  In  the  mail-handling  room  the  end  wall  was  moved 
out  of  plumb  by  the  earthquake,  and  the  enameled-brick  covering  of 
several  columns  was  shaken  off.  The  only  damage  done  by  fire  was  in 
the  district-court  room,  in  the  north  corner  of  the  third  floor,  which 
caught  from  without  and  was  burned  out,  together  with  two  adjacent 
rooms  on  the  northwest  front.  On  the  northeast  end  of  the  first  floor 
the  exterior  stonework  was  also  spalled  by  fire. 

A very  considerable  amount  of  damage  was  done  by  the  dynamiting 
of  near-by  buildings,  which  was  so  severe  as  to  smash  the  glass  and 
blow  out  the  window  and  door  frames.  In  many  places  the  marble 
wainscoting  on  the  opposite  side  of  the  corridor  was  shaken  loose. 
Probably  20  per  cent  of  the  injury  done  to  the  building  is  in  the 
glass,  marble,  and  finish.  The  building  is  substantial,  and  the  mate- 
rials and  workmanship  are  first  class. 

RIALTO  BUILDING. 

The  eight-story  Rialto  Building,  at  the  southwest  corner  of  Mis- 
sion and  New  Montgomery  streets,  had  a steel  frame  and  reenforced 
cinder-concrete  floors.  The  partitions  were  of  hollow  tile  and  the 
ceilings  of  suspended  expanded  metal,  plastered.  The  columns  were 
fireproofed  with  two  layers  of  plastered  expanded  metal  for  all  floors 
except  the  basement,  where  only  one  layer  was  used.  The  corridors 
had  mosaic  floors,  and  the  stairways  were  of  cast  iron  with  marble 
treads. 

The  building  was  considerably  racked  by  the  earthquake  and  was 
further  damaged  by  fire  and  dynamiting  (PI.  XL VIII,  B).  The 
fire  was  only  moderately  hot,  but  was  sufficient  to  destroy  the  fire- 
proofing of  two  columns  in  the  northeast  corner  of  the  basement,  so 
that  they  failed  by  buckling  (PI.  XLVIII,  A),  causing  extensive 
wrecking  of  the  upper  floors.  The  failure  of  the  column  protection 
was  caused  by  the  expansion  of  a pipe  inside  of  it.  The  terra  cotta 
around  the  entrance  to  the  building  was  cracked  by  the  earthquake. 

ST.  FRANCIS  HOTEL. 

The  twelve-story  St.  Francis  Hotel,  in  West  Union  square,  at  the 
corner  of  Geary  and  Powell  streets,  was  of  a modern  type,  having  a 
steel  skeleton,  reenforced-concrete  floors,  with  suspended  ceilings  plas- 


46  THE  SAN  FRANCISCO  EARTHQUAKE  AND  EIRE. 

tered  on  wire  lath.  The  fireproofing  of  beams  and  girders  in  the 
basement  and  first  floor  was  concrete ; in  the  upper  floors  it  was  wire 
lath  and  plaster.  The  columns  of  the  first  floor  were  fireproofed  with 
concrete,  those  in  the  basement  with  brick,  and  on  the  upper  floors 
4-inch  hollow  tile  was  used.  On  the  first  floor  the  concrete  was 
omitted  for  18  inches  at  the  top  and  a cap  of  plaster  of  Paris  used; 
this  was  a serious  mistake  and  might  have  caused  trouble. 

The  stone  was  slightly  spalled  by  fire  and  on  the  front  was  slightly 
damaged  by  the  earthquake.  The  enameled  bricks  of  the  light  well 
were  badly  spalled  by  heat.  Two  columns  failed  by  buckling.  The 
fire  was  not  severe,  and  the  damage  was  not  very  great. 

SCOTT  BUILDING. 

The  Scott  Building,  on  the  south  side  of  Mission  street  between 
First  and  Fremont  streets,  was  a four-story  structure  with  a man- 
sard roof.  Machinery  sales  rooms  occupied  the  two  lower  floors, 
printing  and  lithographing  offices  the  upper.  The  building  was  con- 
structed of  steel  girders  and  beams,  with  reenforced-concrete  floors, 
suspended  ceilings  plastered  on  metal  lath,  and  unprotected  cast- 
iron  columns.  The  curtain  walls  were  carried  on  steel  work  which 
was  unprotected  over  the  windows. 

The  mansard  roof  and  the  upper  part  of  the  walls  were  destroyed 
by  the  earthquake.  The  western  section  was  wrecked  by  dynamite. 
The  ceilings  failed,  and  the  stonework  spalled  slightly.  The  fire 
was  not  severe,  to  judge  from  the  appearance  of  the  undamaged 
naked  cast-iron  columns. 

SECURITY  SAVINGS  BANK. 

The  Security  Savings  Bank,  a two-story  building  on  Montgomery 
street  between  California  and  Pine  streets,  received  its  principal 
damage  from  the  falling  walls  of  an  adjacent  building.  The  granite 
and  marble  front  was  slightly  spalled  by  the  earthquake. 

SHREVE  BUILDING. 

The  eleven-story  Shreve  office  building,  at  the  northwest  corner  of 
Post  and  Grant  streets,  was  constructed  with  steel  frame,  reenforced- 
concrete  floors,  and  suspended  ceilings  plastered  on  metal  lath.  The 
columns  above  the  second  floor  were  fireproofed  with  3 -inch  hollow 
tile ; those  below  with  concrete.  This  latter  protection,  as  well  as  the 
concrete  floors,  is  in  first-class  condition.  The  difference  in  efficiency 
between  the  concrete  and  hollow-tile  protection  for  columns  is  clearly 
demonstrated,  the  former  being  in  excellent  shape,  whereas  the  latter 
failed,  resulting  in  a number  of  buckled  columns. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


47 


SLOANE  BUILDING. 

The  seven-story  Sloane  Building,  on  Post  street  between  Grant  and 
Kearney  streets,  had  bearing  walls  of  terra  cotta,  brick  and  terra- 
cotta trimmings,  and  a framework  of  cast-iron  columns  and  steel 
beams  and  girders.  The  partitions  and  fireproofing  were  of  ex- 
panded metal,  plastered,  and  the  floors  were  of  concrete,  reenforced 
with  expanded  metal.  All  columns  except  those  in  the  basement 
were  fireproofed  with  expanded  metal,  plastered. 

There  is  every  indication  of  a very  hot  fire  in  the  basement,  which 
buckled  several  of  these  unprotected  columns,  causing  a collapse  in 
the  central  portion  of  the  building  (PL  XLIX,  A). 

SPRING  VALLEY  WATER  COMPANY’S  BUILDING. 

The  City  of  Paris  Dry  Goods  Company  occupied  the  two  lower 
floors  of  the  Spring  Valley  Water  Company’s  building,  at  the  south- 
east corner  of  Geary  and  Stockton  streets,  the  remaining  four  stories 
being  used  fo£  office  purposes.  The  building,  a general  rear  view  of 
which  is  shown  in  PL  L,A,  had  a steel  skeleton,  the  partitions,  column 
protection,  and  floor  arches,  the  lower  web  of  which  spalled  off  exten- 
sively, being  of  hollow  tile.  The  floor  arches  were  topped  with  cinder 
concrete  and  covered  with  wood.  The  columns  in  the  southeast  corner 
of  the  basement  buckled,  and  the  upper  stories  collapsed.  The  hollow- 
tile  partitions  were  in  bad  condition,  and  the  2-inch  tile  on  col- 
umns failed  generally.  Where  the  tile  ceilings  were  unprotected 
the  webs  spalled  extensively;  where  there  was  a suspended  ceiling 
remaining  in  position  the  tiles  were  in  fair  condition.  The  cast-iron 
stairways  with  marble  treads  were  also  damaged.  There  were  a few 
slight  earthquake  cracks  along  the  Stockton  street  side,  and  the  south 
wall  had  a vertical  crack. 

UNITED  STATES  SUBTREASURY. 

The  four-story  brick  subtreasury  building,  on  Montgomery  street 
between  Commercial  and  Clay  streets,  had  rolling  shutters  on  the 
lower  front  windows  and  a combination  of  wood  and  concrete  floors. 
The  wood  burned,  causing  the  collapse  of  that  portion  of  the  build- 
ing. The  remainder  of  the  concrete-floor  portion  seemed  to  be  in  fair 
condition. 

UNION  TRUST  COMPANY’S  BUILDING. 

The  Union  Trust  Company’s  ten-story  office  building,  on  the  cor- 
ner of  Market  and  Montgomery  streets,  was  constructed  with  a steel 
frame.  The  front  walls  of  the  first  two  stories  were  granite;  the 


48 


THE  SAN  FRANCISCQ  EARTHQUAKE  AND  FIRE. 


remaining  walls  were  of  pressed  terra-cotta  brick,  with  terra-cotta 
trimmings.  The  floors  and  partitions  were  of  hollow  tile,  and  the 
girders,  beams,  and  columns  were  fireproofed  with  the  same  material. 
The  floors  were  topped  with  cinder  concrete  covered  with  wood, 
except  in  the  corridors,  where  cement  finish  was  used.  The  cast-iron 
stairways  had  marble  treads.  The  granite  walls  were  spalled 
around  the  openings  by  fire.  The  hollow-tile  partitions  failed  ex- 
tensively, and  the  lower  web  of  the  floor  tile  spalled  over  large 
areas.  The  fire  was  not  intense,  and  the  steel  appeared  to  be  in 
fair  condition  except  on  the  ninth  and  tenth  floors.  The  extent  of 
the  damage  can  be  seen  in  PI.  L,  B , q view  on  the  ninth  floor. 
The  steel  trusses  on  the  tenth  floor  were  very  much  distorted  by  heat, 
owing  to  the  failure  of  the  hollow-tile  fireproofing. 

VOLKMAN  BUILDING. 

The  lower  floor  of  the  Volkman  Building,  on  the  north  side  of 
Jackson  street  between  Montgomery  and  Sansome  streets,  opposite 
the  unburned  block  near  the  appraisers’  building,  was  occupied 
by  a branch  of  the  post-office.  The  structure  was  surrounded  on 
the  sides  and  rear  by  completely  gutted  buildings,  and  its  es- 
cape was  probably  due  to  its  protected  openings.  The  windows 
were  glazed  with  wire  glass  and  the  sash  and  frames  were  metal 
covered.  The  rear  doors  were  equipped  with  Kinnear  rolling  shut- 
ters. A few  windows  were  so  badly  damaged  that  they  will  have  to 
be  replaced,  but  the  building  was  only  slightly  injured,  for  the  fire 
did  not  gain  a foothold. 

WELLS-FARGO  BUILDING. 

The  six-story  Wells-Fargo  Building,  on  the  northeast  corner  of 
Mission  and  Second  streets,  is  devoted  exclusively  to  Wells,  Fargo 
& Co.’s  express  business.  It  has  a steel  skeleton,  self-supporting 
walls,  and  reenforced-concrete  floors.  The  ceilings  are  of  plastered 
wire  lath,  as  are  also  the  hollow  partitions  and  the  fireproofing  on 
the  columns.  The  outside  walls  are  of  granite  for  the  first  two 
^stories  and  pressed  brick  and  terra  cotta  for  the  remaining  stories. 
The  openings  into  the  air  and  light  well  were  of  metal  frame,  glazed 
with  wire  glass. 

This  building  shows,  especially  in  the  Mission  street  front,  the 
racking  effect  of  the  earthquake.  The  marble  treads  of  the  cast- 
iron  stairways  were  considerably  damaged  by  the  fire,  and  the  marble 
wainscoting  of  the  corridors  was  thrown  down  by  the  earthquake. 
The  window  frames  in  the  light  well  (PI.  XLIX,  B)  were  warped 
by  the  fire,  which  also  spalled  the  terra-cotta  trim. 


RECOMMENDATIONS  OF  INSURANCE  BOARDS. 


49 


ASPECTS  OF  THE  FIRE  DISASTER. 

The  San  Francisco  fire,  which  lasted  three  days,  was  one  of  the 
greatest  conflagrations  of  recent  times.  The  loss  by  fire  was  greater 
than  it  should  have  been,  by  reason  of  the  failure  of  the  cast-iron 
water  mains  in  the  city ; although  the  loss  must  necessarily  have  been 
great  because  of  the  character  of  the  buildings,  90  per  cent  of  which 
were  frame.  This  disaster  demonstrated  -that  the  lessons  from  the 
Chicago  and  Baltimore  fires  are  still  unlearned.  The  same  faults  in 
construction  continue  to  be  repeated.  The  only  sure  way  to  remedy 
grave  defects  of  this  character  is  to  enact  strict  building  laws  which 
will  compel  an  observance  of  the  essentials  for  fireproof  structures. 

The  conditions  at  San  Francisco  were  unusual,  and  even  had  not 
the  water  supply  failed  it  is  doubtful  whether  they  could  have  been 
controlled,  for  the  reason  that  it  would  have  been  impossible  for  the 
fire  department  to  handle  efficiently  so  many  fires  at  a time,  especially 
as  there  were  so  many  nonfireproof  structures.  Large  conflagrations 
demonstrate  that  there  is  no  such  thing  as  a fireproof  building.  To 
label  one  as  such  is  bad  practice,  since  it  gives  a false  sense  of 
security  and  induces  a relaxing  of  necessary  precautions. 

FIRE  HISTORY  AND  RECOMMENDATIONS  OF  INSURANCE  BOARDS. 

It  is  claimed  that  the  recorded  destruction  by  fires  in  San  Fran- 
cisco up  to  1899  was  excessive,  showing  an  average  loss  between  two 
and  three  times  that  expected  in  cities  having  ordinary  fire  protec- 
tion. In  every  year  since  1899,  except  1903,  although  the  number  of 
fires  increased  materially,  the  average  loss  per  fire  remained  moder- 
ate. In  any  of  these  years  the  number  of  fires  involving  losses  of 
$40,000  or  more  did  not  exceed  two.  In  1903  there  were  ten  large 
fires,  each  involving  a loss  of  more  than  $40,000,  thus  bringing  the 
total  up  to  a high  figure ; and  at  each  of  these  fires  the  greater  por- 
tion of  the  loss  was  to  the  contents  rather  than  to  the  buildings. 

In  October,  1905,  a board  of  fire-insurance  experts  presented  the 
report  of  an  examination  made  under  the  direction  of  the  National 
Board  of  Fire  Underwriters  on  the  fire-hazard  conditions  of  San 
Francisco.  This  report  is  extremely  interesting  and  shows  clearly 
how  a body  of  trained  experts  can  accurately  locate  defects  and  pre- 
dict the  consequences  likely  to  result  from  them.  The  criticisms  and 
recommendations  embodied  in  the  report  are  particularly  pertinent 
to  San  Francisco;  and  when  the  conditions  prior  to  the  great  fire  are 
considered,  the  conclusion  must  be  inevitable  that  no  other  result  of 
these  conditions — a general  conflagration  which  swept  the  city — 
could  reasonably  have  been  expected.  Attention  was  called  to  the 
following  principal  features  of  construction  affecting  the  fire  hazard 


50 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


in  the  business  district:  (1)  Bad  exposures  and  unprotected  open- 
ings; (2)  poor  construction;  (3)  an  absence  of  sprinklers  or  of  any 
of  the  modern  protective  devices;  and  (4)  excessive  height  in  non- 
fireproof  structures.  It  is  stated  that  in  the  congested  district  about 
2.2  per  cent  were  fireproof,  68.3  per  cent  were  wooden  joisted  brick, 
and  29.5  per  cent  were  frame  buildings.  A very  bad  feature  lay  in 
the  fact  that  a large  number  of  so-called  “ fireproofs  ” were  sur- 
rounded by  nonfireproofs.  The  mixture  of  dwellings  and  minor 
mercantile  buildings  surrounding  the  congested-value  district  also 
greatly  increased  the  hazard. 

The  board  recommended  the  municipal  ownership  of  the  water  sup- 
ply. They  considered  the  present  supply  ample  in  amount  for  the 
existing  requirements,  but  subject  to  a decided  probability  of  local 
failure  in  emergencies,  owing  to  faults  in  the  distribution  system. 
They  deemed  it  very  desirable  to  increase  the  capacity  of  the  existing 
system  and  to  install  at  the  earliest  possible  date  a separate  fire-main 
system,  and  recommended  that  all  dead  ends  of  pipe  mains  be  con- 
nected with  the  network  wherever  practicable.  They  advised  that 
the  system  of  distribution  be  equipped  with  a sufficient  number  of 
gate  valves,  so  located  that  no  single  case  of  accident,  breakage,  or 
repair  to  the  pipe  system  would  necessitate  the  shutting  from  service 
of  a length  of  main  greater  than  the  side  of  a single  block  (a  maxi- 
mum of  500  feet)  in  important  mercantile  manufacturing  districts, 
or  than  two  sides  of  a single  block  (a  maximum  of  800  feet)  in  other 
districts. 

The  building  code  was  found  to  be  satisfactory  on  the  whole,  but 
the  board  recommended  that  it  be  so  amended  as  to  limit  floor  areas, 
provide  for  the  protection  of  exposed  openings  in  fireproof  build- 
ings, and  encourage  the  use  of  modern  protective  devices  and  construc- 
tions, such  as  sprinkler  equipments,  automatic  fire  doors,  wire  glass, 
etc.  They  recommended  that  prompt  measures  be  taken  to  relieve 
the  hazardous  conditions  in  narrow  streets  by  widening  the  streets 
or  enforcing  adequate  window  protection,  or  both,  and  advised  that 
automatic  sprinkler  equipments  be  required  in  all  buildings  which  by 
reason  of  their  size,  construction,  or  occupancy,  singly  or  combined, 
might  act  as  conflagration  breeders.  The  potential  hazard  was  con- 
sidered very  severe,  in  view  of  the  exceptionally  large  areas  and 
great  heights  of  many  buildings  and  of  their  highly  combustible 
nature  by  reason  of  sheathed  walls  and  ceilings,  numerous  unpro- 
tected openings  and  light  wells,  and  the  general  absence  of  fire 
breaks,  taken  in  conjunction  with  the  presence  of  interposed  frame 
buildings  and  the  comparatively  narrow  streets.  These  numerous 
and  mutually  aggravating  conflagration  breeders,  considered  in  con- 
nection with  the  almost  total  lack  of  sprinklers  and  general  absence 


FIRE-RESISTING  QUALITIES  OF  STRUCTURES,,  ETC. 


51 


of  modern  protective  devices,  and  the  prevailing  high  winds,  made 
the  probability  feature  alarmingly  great.  . 

They  advised  that  the  inadequate  force  of  four  building  inspectors 
be  at  least  doubled,  and  that  the  building  laws  be  rigidly  and  im- 
partially enforced. 

They  found  the  fire  department  to  be  an  efficient  force,  well  organ- 
ized under  an  exceptionally  competent  chief,  and  though  weak  in 
powerful  engines,  otherwise  fairly  well  equipped,  the  number  of 
engine  companies  being  particularly  large. 

In  their  report  the  board  summarized  the  situation  in  San  Fran- 
cisco as  follows : 

While  two  of  the  five  sections  into  which  the  congested-value  district  is 
divided  involve  only  a mild  conflagration  hazard  within  their  own  limits,  they 
are  badly  exposed  by  the  others,  in  which  all  the  elements  of  the  conflagration 
hazard  are  present  to  a marked  degree.  Not  only  is  the  hazard  extreme 
within  the  congested-value  district,  but  it  is  augmented  by  the  presence  of  a 
compact  surrounding,  great-height,  large-area,  frame-residence  district,  itself 
unmanageable  from  a fire-fighting  standpoint  by  reason  of  adverse  conditions 
introduced  by  the  topography.  In  fact,  San  Francisco  has  violated  all  under- 
writing traditions  and  precedents  by  not  burning  up ; that  it  has  not  done  so  is 
largely  due  to  the  vigilance  of  the  fire  department,  which  can  not  be  relied  upon 
indefinitely  to  stave  off  the  inevitable. 

FIRE-RESISTING  QUALITIES  OF  STRUCTURES  AND  STRUCTURAL 

MATERIALS. 

The  fire  which  has  practically  destroyed  San  Francisco  has  more 
than  fulfilled  this  prophecy.  The  destruction  was  greater  than  in 
the  Baltimore  fire  because  the  fire  was  hotter,  owing,  as  has  been 
pointed  out,  to  the  inflammable  surroundings  and  the  unprotected 
openings,  and  to  the  unchecked  sway  of  the  flames.  The  heat  was 
so  intense  that  sash  weights  and  glass  melted  and  ran  together  freely. 
In  some  places  the  edges  of  broken  cast-iron  columns  softened,  the  tin 
coating  in  piles  of  tinned  plate  volatilized,  even  in  the  middle  of  the 
piles,  and  nails  were  softened  sufficiently  to  weld  together.  (See  also 
PL  LI,  A.)  The  maximum  temperature,  lasting  for  a few  minutes 
in  each  locality,  was  probably  2,000°  or  2,200°  F.,  while  the  average 
temperature  did  not  exceed  1,500°  F. 

Nearly  all  the  so-called  “ fireproofs  ” were  gutted  and  their  con- 
tents destroyed,  the  fire  damage  done  to  these  buildings  being  fully 
60  per  cent.  The  early  collapse  of  protected  steel  frames  owing  to 
the  failure  of  the  fireproofing  was  of  common  occurrence.  The 
extent  of  the  damage  to  a building  from  fire  can  be  determined 
only  after  the  debris  and  wreckage  have  been  removed  and  will 
then  be  found  to  be  much  greater  than  was  at  first  supposed.  This 
is  particularly  true  of  steel  structures  in  which  the  effect  of  fire  is 
partly  hidden  by  the  debris. 


52 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


Of  perhaps  thirty  fireproofs  of  good  height'  with  reenforced- 
concrete  floors,  all  but  two  had  steel  frames.  Steel  beams  and 
columns  were  generally  protected  with  metal  lath  and  plaster,  cinder 
concrete,  or  terra-cotta  tile.  Practically  all  floor  construction  con- 
sisted either  of  hollow  terra-cotta  tile  or  reenforced  concrete.  Ceil- 
ings of  light  angles  and  metal  lath,  plastered,  suspended  from  floors, 
served  as  additional  means  of  fireproofing,  by  keeping  the  fire  from 
coming  into  direct  contact  with  the  flooring  material.  Steel  beams 
in  many  buildings  had  no  protection,  even  where  concrete  filled, 
except  this  subceiling.  The  lower  webs  of  floor  tile  came  off  to  per- 
haps a greater  extent  than  in  the  Baltimore  fire.  It  is  said  to  be 
impossible  to  procure  a suitable  hard-wood  sawdust  on  the  Pacific 
coast,  such  as  is  required  in  the  manufacture  of  porous  terra-cotta 
tile.  The  tile  used  is  therefore  denser  and  of  poorer  quality.  The 
behavior  of  reenforced-concrete  floors  was  most  excellent. 

Partition  walls  were  in  a very  few  buildings  of  brick.  As  a rule, 
however,  they  were  either  of  3-inch  hollow  terra-cotta  tile  or  metal 
lath,  plastered. 

The  matter  of  column  protection  is  very  important,  as  the  number 
of  failures  in  the  San  Francisco  fire  was  particularly  large,  especially 
in  the  Fairmount  Hotel  (PI.  XXXIV).  Unprotected  cast-iron  col- 
umns failed  as  a result  of  unequal  expansion  caused  by  the  lugs.  A 
few  light  cast-iron  columns  filled  with  concrete  came  through  without 
damage,  and  at  the  Academy  of  Sciences  (PI.  XXIV,  A),  as  already 
described,  cast  iron  failed  around  a concrete  core,  which  carried  the 
load.  Brick-filled  columns  gave  fair  satisfaction,  but  concrete-pro- 
tected columns  afforded  the  best  results.  The  question  of  fireproof- 
ing, however,  is  one  of  degree,  being  dependent  on  the  intensity  and 
duration  of  the  fire.  A column  may  be  fireproofed  sufficiently  for  an 
office  building,  but  entirely  too  little  for  a warehouse;  or  a column 
which  may  be  suitable  for  the  upper  stories  may  fail  in  the  basement, 
as  in  the  Kamm  Building  (p.  40).  Again,  the  practice  of  running 
piping  back  of  the  fireproofing  on  columns,  especially  if  the  fireproof- 
ing is  of  hollow  tile,  is  extremely  bad.  Many  failures  were  caused  by 
the  expansion  of  such  piping  throwing  off  the  terra-cotta  tile.  Con- 
crete is  probably  the  best  fireproofing  material,  because,  as  shown  by 
experience,  its  stiffness  will  enable  it  to  support  not  only  the  steel 
within,  if  the  latter  is  softened  by  the  heat,  but  perhaps  the  structure 
itself.  The  following  types  of  column  protection  were  used  in  San 
Francisco  buildings : (1)  Plaster  on  wire  lath,  both  single  and  double 
layers,  the  latter  having  a dead  air  space;  (2)  single  terra-cotta  tile; 
(3)  concrete;  (4)  concrete  covered  with  terra-cotta  tile;  (5)  brick. 

Of  the  fire  loss,  perhaps  75  per  cent  was  in  the  trim  and  ornamental 
work.  Inflammable  woodwork  in  the  corridors,  doors,  and  windows 
proved  a source  of  great  loss,  and  should  be  eliminated  for  orna- 


FIRE-RESISTING  QUALITIES  OF  STRUCTURES,  ETC.  53 

mental  purposes.  The  behavior  of  the  metal-covered  woodwork  in 
the  Kohl  and  other  buildings  was  satisfactory  and  immensely  better 
than  that  of  the  naked  wood.  It  is  certain  that  a building  may  be 
finished  and  trimmed  and  even  decorated  with  noninflammable  mate- 
rials. Although  the  additional  security  of  such  materials  in  case  of 
fire  does  not  appeal  to  owners  and  architects  as  compensating  for 
their  extra  cost  in  comparison  with  wood  or  other  inflammable  mate- 
rials, the  building  laws  should  nevertheless  compel  this  type  of 
construction. 

The  loss  in  ornamental  stonework  was  particularly  great,  especially 
in  the  case  of  marble,  which  in  many  structures  was  completely 
calcined.  Brickwork  suffered  most  from  the  earthquake  and  least 
from  fire,  and  sandstone  splintered  less  than  granite,  which  suf- 
fered severely,  a number  of  badly  spalled  columns  showing  how 
futile  this  material  is  for  other  than  ornamental  purposes.  Con- 
crete proved  superior  to  brick  as  a fireproofing  medium. 

It  is  estimated  that  over  80  per  cent  of  the  so-called  “ fireproof  ” 
safes  failed.  Many  valuable  records  and  much  other  property  were 
thereby  destroyed.  An  ordinary  fireproof  safe  was  of  absolutely  no 
value,  and  the  contents  of  nearly  every  one  were  destroyed.  In  many 
office  buildings  so-called  fireproof  vaults  were  constructed  of  hollow 
tile  or  plastered  metal  lath,  being  formed  partly  by  the  partitions 
of  the  rooms,  and  were  so  flimsy  that  they  yielded  readily  to  the 
flames.  In  PI.  LII  can  be  seen  groups  of  so-called  “ fireproof  safes,” 
many  with  walls  20  inches  or  more  thick,  which  failed  to  serve  the 
purpose  for  which  they  were  designed.  PI.  LII,  B , shows  part  of  a 
collection  of  over  50  of  these  “ safes  ” whose  contents  were  destined. 
In  a number  of  jeweler’s  safes  silver  and  other  precious  metals  were 
melted.  The  warping  of  the  doors  also  resulted  in  the  loss  of  the 
contents  in  many  vaults,  even  where  they  were  otherwise  well  de- 
signed. In  short,  fireproof  vaults  and  safes  behaved  in  the  San 
Francisco  fire  very  much  as  they  did  in  the  Baltimore  fire.  Little 
progress  seems  to  have  been  made  toward  the  production  of  a satis- 
factory fireproof  safe.  The  only  really  fireproof  vault  is  one  with 
brick  or  concrete  walls  not  less  than  10  inches  thick.  The  cement- 
filled  metal  safe  proved  to  be  a very  good  type  of  fireproof.  Even 
in  well-designed  safes  and  vaults,  great  care  must  be  exercised  in 
opening  them  after  they  have  been  exposed  to  fire.  Time  should  be 
allowed  for  the  temperature  in  the  interior  to  become  reduced  to 
somewhere  near  the  temperature  of  the  surrounding  air,  as  otherwise 
the  contents  may  be  destroyed  by  spontaneous  combustion  on  exposure 
to  the  air.  Pl.  LII,  A,  is  a view  of  one  of  the  oldest  vaults  in  San 
Francisco,  that  of  the  old  Wells,  Fargo  & Co.’s  Express,  which  passed 
the  fire  test  satisfactorily. 

The  writer  is  of  the  opinion  that  the  present  commercial  hollow 
7171— Bull.  324—07 5 


54  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

terra-cotta  tile  is  largely,  if  not  entirely,  devoid  of  merit  for  fire- 
proofing purposes.  Even  when  it  is  of  the  best  grade  and  workman- 
ship it  can  hardly  be  considered  a first-class  building  material.  At 
a comparatively  low  temperature  the  tiles  fail,  the  thin  webs  spalling 
from  unequal  expansion.  A more  porous  tile,  with  thicker  webs 
keyed  together  and  laid  in  Portland-cement  mortar  with  tight  joints, 
would  unquestionably  be  more  suitable  for  the  purpose.  It  may  be 
true  that  in  case  of  repairs  after  a fire  damaged  tile  of  the  usual 
commercial  type  can  readily  be  detected  and  renewed.  Terra-cotta 
tiling  may,  however,  allow  sufficient  heat  to  pass  through  it  to  soften 
slightly  the  steel  member  which  it  encases  and  still  remain  in  posi- 
tion, thus  hiding  the  defect.  Several  examples  of  this  condition  were 
found. 

The  advocates  of  terra-cotta  tile  contend  that  concrete  may  be 
seriously  damaged  by  dehydration  without  noticeable  change  in  its 
appearance.  While  this  contention  may  be  justified,  it  should  be 
noted  that  any  weakness  or  softness  may  be  as  readily  detected  and 
repaired  in  concrete  as  in  terra  cotta.  Concrete,  moreover,  has  the 
great  advantage  of  being  a nonconductor  of  heat,  and  so  will  with- 
stand a prolonged  heat  before  the  damage  extends  to  any  great  depth ; 
and  it  usually  remains  in  place,  maintaining  its  protective  qualities. 
The  value  of  a structure  or  of  a method  of  fireproofing  is  determined 
largely  by  ascertaining  what  portion  of  the  structure  is  left  avail- 
able for  use  after  the  fire.  The  word  “ fireproof  ” is  of  course  a 
misnomer,  for  no  building  is  absolutely  fireproof;  and  the  resist- 
ance offered  to  fire  is  one  of  degree  only,  for  if  the  heat  be  sufficiently 
high  and  prolonged,  nothing  can  withstand  it.  The  best  materials 
are  nonconductors  of  heat,  having  high  fusing  points.  At  high 
temperature  concrete  loses  its  water  of  crystallization,  but  the  depth  to 
which  this  dehydration  goes  and  the  rate  at  which  it  takes  place  are 
the  factors  that  determine  the  effectiveness  of  the  material.  The 
heat  insulation  afforded  by  concrete  is  of  a high  order,  and  to  obtain 
the  best  results  a sufficient  thickness  must  be  applied.  This  required 
thickness  is  naturally  a variable  quantity;  2 inches,  or  even  1 inch, 
may  be  sufficient  for  an  office  building,  but  would  be  inadequate  for 
a,  warehouse.  These  remarks  concerning  concrete  also  apply  to  all 
other  forms  of  fireproofing.  The  prime  point  on  which  information 
should  be  procured  is  the  thickness  of  the  insulation  for  proper  pro- 
tection against  fire. 

Perhaps  the  most  important  problem  is  that  of  protecting  a build- 
ing from  fire  from  without.  To  do  so  means  the  protecting  of  all 
openings  and  the  making  of  the  roof  equally  as  resistant  as  the  other 
parts  of  the  structure.  Buildings  should  be  self-contained — that  is, 
protected  against  exterior  fires  and  capable  of  fighting  fire  from  the 
inside;  and  in  earthquake  countries,  where  the  outside  water  service 


WATER  SUPPLY  AND  OTHER  MEANS  OF  FIGHTING  FIRE.  55 


is  likely  to  fail  through  rupture  of  the  steel  mains,  it  is  highly 
desirable  to  have  an  independent  supply,  as  from  an  artesian  well, 
with  the  necessary  pumps  and  service  pipe. 

In  the  matter  of  fireproofing,  certain  definite  recommendations  may 
be  deduced  from  the  San  Francisco  conflagration,  as  follows: 

1.  Exterior  openings  should  be  protected  by  the  use  of  metal 
frames  or  metal-covered  frames  with  wire  glass,  or  exterior  iron 
shutters  or  interior  metal-covered  shutters,  or  both  exterior  and 
interior  shutters. 

2.  The  structural  members,  especially  the  columns,  should  be  better 
protected,  preferably  with  solid  concrete;  they  may  be  filled  with 
brick  and  covered  with  terra  cotta  or  with  a double  layer  of  cement- 
plastered  metal  lath,  with  an  air  space  between. 

3.  There  should  be  a better  type  of  partition,  the  present  plastered 
metal  lath  or  hollow  terra-cotta  tile  being  inadequate.  Reenforced- 
concrete  partitions  are  much  more  efficient. 

4.  All  combustible  trim  should  be  eliminated.  The  fire  loss  from 
this  item  is  high,  and  it  should  be  so  designed  as  to  be  replaced  readily 
and  cheaply. 

5.  Attic  floors  and  roofs  should  be  designed  to  resist  fire.  In  many 
buildings  the  roof  members  were  not  fireproofed  and  their  failure 
caused  great  damage. 

6.  Buildings  should  be  so  arranged  that  the  fire  could  be  confined 
to  a single  room. 

WATER  SUPPLY  AND  OTHER  METHODS  OF  FIGHTING  FIRE. 

In  connection  with  the  matter  of  the  fireproof  construction  of 
buildings  above  referred  to,  certain  suggestions  may  be  made  in 
regard  to  private  and  public-  facilities  for  fighting  fire,  as  follows : 

1.  An  independent  water  supply  and  other  facilities  for  fighting 
the  fire  from  either  within  or  without  should  be  provided. 

2.  Another  ver}^  important  problem,  at  least  so  far  as  San  Fran- 
cisco is  concerned,  is  that  of  the  public  water  supply.  The  failure 
of  a gridiron  system  of  cast-iron  pipes  seriously  cripples  a water 
supply,  no  matter  how  large  may  be  the  storage.  It  is  also  evident 
that  greater  care  must  be  exercised  in  the  laying  of  these  mains, 
especially  in  filled  ground  or  alluvial  soil,  where  failures  are  likely 
to  occur.  A system  of  by-passes  should  be  provided,  so  arranged  as 
to  permit  the  cutting  out  of  portions  which  are  broken  or  otherwise 
damaged,  and  some  system  should  be  installed  for  quick  repairs  under 
emergency  conditions. 

3.  A high-pressure  service  operated  from  the  bay,  using  salt 
water,  would  also  be  an  essential  feature.  This  service  might  neces- 
sitate a floating  pumping  station,  as  recommended  by  the  National 
Board  of  Fire  Underwriters. 


56 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


4.  The  use  of  explosives,  such  as  dynamite,  for  fighting  a fire 
should  be  greatly  restricted  and  intrusted  to  experts  only,  or  else 
abandoned.  It  is  extremely  doubtful  whether  the  progress  of  a fire 
can  be  checked  by  dynamiting  in  advance  of  the  fire  without  the 
removal  or  thorough  wetting  of  the  debris.  Such  procedure  would 
have  been  impossible  in  San  Francisco,  as  the  water  supply  was 
unavailable  and  it  was  impossible  to  carry  away  the  wreckage.  The 
indiscriminate  dynamiting  did  more  harm  than  good,  for  the  reason 
that  the  concussions  injured  the  surrounding  buildings,  as  shown,  for 
example,  by  the  extensive  damage  done  at  the  post-office.  Back  firing 
would  have  been  equally  bad,  because  to  apply  this  method  success- 
fully plenty  of  water  for  controlling  the  fire  is  necessary.  A fire 
stop  is  the  best  way  of  checking  a conflagration,  and  a fireproof 
structure  makes  the  best  fire  stop  if  it  has  well-protected  openings. 

GENERAL  EESSOKS  OF  THE  EARTHQUAKE  AND  FIRE. 

In  considering  the  results  of  the  destruction  which  was  wrought  by 
the  earthquake  and  fire  there  appear  certain  salient  features  from 
which  conclusions  may  be  drawn.  In  regard  to  the  possibility  of  the 
erection  of  an  earthquake-proof  structure,  it  is  apparent  and  univer- 
sally admitted  that  it  would  be  impossible  to  build  on  the  fault  line 
a structure  which  could  withstand  the  effect  of  a slip.  Furthermore, 
it  is  realized  that  in  building  near  the  fault  on  soft  or  alluvial  soil 
extra  precautions  must  be  taken ; for  example,  location  of  the  San 
Francisco  water  mains  in  ground  of  this  character  was  unwise,  since 
it  is  difficult  to  design  a waterworks  system  capable  of  resisting  the 
effect  of  settling  of  the  ground.  The  importance  of  proper  construc- 
tion and  distribution  of  the  water  mains  in  districts  liable  to  earth- 
quakes is  demonstrated  by  the  fact  that  the  greatest  damage  in  San 
Francisco,  fully  85  per  cent  of  the  total,  was  by  fire.  The  action  of 
the  earthquake  in  starting  the  fires  which  grew  to  a great  conflagra- 
tion seems  insignificant  compared  to  the  breaking  of  the  water  mains, 
which  left  the  city  defenseless  against  the  flames. 

The  comparatively  great  destruction  wrought  by  the  earthquake 
to  structures  located  on  filled  ground  or  alluvial  soil  has  already  been 
pointed  out.  The  destruction  in  San  Francisco  was  confined  largely 
to  buildings  located  on  the  alluvium  of  the  flats  or  on  the  filled 
ground  of  old  watercourses.  That  structures  can  be  built,  however, 
which  will  satisfactorily  meet  even  such  conditions  when  adequate 
foundations  are  provided,  extending  through  the  soft  material  to  a 
solid  base,  is  demonstrated  by  the  behavior  of  such  buildings  as  the 
Leland  Stanford  Junior  Museum  (PI.  XIV,  A)  and  Roble  Hall,  at 
Stanford  University;  the  Government  buildings  (Pis.  XXVIII,  A ; 
XXXVIII;  XLII,  B ; XLIII;  XLIV),  and  the  Call  and  other 
buildings  in  San  Francisco. 


GENERAL  LESSONS  OE  THE  EARTHQUAKE  AND  EIRE.  57 


The  structures  which  suffered  most  from  the  earthquake  were — 

1.  The  municipal  and  county  buildings.  The  greatest  destruction 
was  sustained  by  these  buildings,  which  were  generally  badly  de- 
signed and  poorly  constructed  of  inferior  materials,  while  the  well- 
built,  substantial  Government  buildings  suffered  less. 

2.  Lightly  and  flimsily  constructed  wooden  buildings.  Well-con- 
structed wooden  buildings  generally  withstood  the  shock,  but  those 
that  were  flimsily  built,  resting  upon  posts  or  equally  insufficient 
foundations,  collapsed,  even  where  they  were  fairly  well  designed. 
The  essentials  of  earthquake-resisting  power  are  vertical  continuity, 
adequate  diagonal  bracing,  and  first-class  foundations. 

3.  Improperly  built  brick  and  stone  structures.  The  brick  walls 
which  failed,  either  by  being  shaken  down  entirely  or  by  shattering, 
were  laid  in  lime  mortar  with  few  header  courses,  and  generally  had 
wooden  frames  with  little  or  no  bracing  and  no  tie  to  the  walls. 
Stone  and  brick  masonry  cracked  diagonally  in  the  form  of  an  X. 
Hollow-tile  partitions  and  masonry  of  brick  or  stone  were  similarly 
cracked,  although  this  injury  was  small  where  Portland -cement 
mortar  was  used.  Where  the  walls  were  laid  with  hard  brick,  with 
plenty  of  headers  and  in  Portland-cement  mortar,  and  were  properly 
tied  to  the  floor  and  roof  members  there  was  little,  if  any,  damage. 
Chimneys  collapsed  most  generally,  breaking  about  halfway  up,  and 
destroyed  in  part  at  least  the  structures  upon  which  they  fell.  While 
the  evidence  was  by  no  means  conclusive,  it  appeared  to  the  writer 
that  brick  stacks  of  circular  section  proved  more  substantial  than 
square  ones.  The  stack  of  the  Valencia  street  power  plant,  which 
was  of  eight-pointed  star  section,  collapsed,  the  part  wdiich  remained 
standing  showing  cracks  at  one  of  two  opposite  reentrant  angles 
almost  to  the  base  (PI.  LIII,  A).  It  is  quite  evident  that  brick 
stacks  and  similar  tall  structures  built  of  brick  or  stone  without 
reenforcement  against  flexure,  or  without  being  guyed,  are  unsuitable 
for  use  in  countries  liable  to  earthquake  shock.  They  should  be  con- 
structed either  of  steel,  guyed,  or,  if  self-supporting,  of  steel  or  reen- 
forced concrete.  (See  also  PI.  XIII,  A.) 

4.  Insufficiently  braced  and  loosely  constructed  steel  structures. 
In  structures  which  were  deficient  in  diagonal  bracing  the  effect  of 
the  earthquake  was  localized  in  the  piers  between  openings  and  cur- 
tain walls  in  characteristic  X cracks.  In  tall  structures  like  the  Call 
Building,  the  tower  of  the  Union  Ferry  Building,  and  others,  the 
diagonal  bracing  that  had  been  installed  proved  insufficient,  and  the 
diagonals  at  about  the  middle  distance  between  the  top  and  base  were 
strained  beyond  the  elastic  limit  of  the  material,  acquiring  a perma- 
nent set,  which  was  indicated  by  a slight  buckling.  It  is  assumed 
that  the  effect  of  earthquake  shock  on  diagonal  bracing  is  equiva- 
lent to  a heavy  wind  pressure,  variously  estimated  at  30  to  50  pounds 


58 


THE  SAN  FRANCISCO  EARTHQUAKE  AN!)  FIRE, 


per  square  inch.  The  writer  believes  that  the  higher  figure  should  be 
used,  because  the  essential  in  satisfactory  earthquake-resistant  design 
is  rigidity,  whereby  the  structure  moves  as  a unit.  Unless  there 
should  be  earthquakes  of  greater  severity  than  the  one  under  discus- 
sion, no  fear  need  be  felt  for  tall  buildings.  It  has  been  fully 
demonstrated  that  a steel  frame  well  braced  diagonally  upon  an 
adequate  foundation  successfully  meets  the  earthquake  requirements ; 
not  even  the  masonry  being  injured  to  any  great  extent. 

Concrete,  especially  reenforced  concrete,  because  of  its  great  ad- 
hesive strength  and  reenforcing  metal,  proved  more  satisfactory 
than  any  other  material.  Its  solid  monolithic  structure  produces  a 
successful  earthquake-resisting  material,  inasmuch  as  it  moves  as  a 
unit;  moreover,  it  offers  a maximum  resistance  to  fire.  The  great 
concrete  dam  of  the  Crystal  Springs  Lake  at  San  Mateo  (PI.  XI,  B ) 
gave  abundant  proof  of  the  substantial  qualities  of  concrete  in  a mass, 
for  although  it  lies  within  a few  hundred  yards  of  the  fault,  it 
suffered  no  damage.  Solid  concrete  floors  proved  satisfactory, 
though  concrete  in  San  Francisco  was  of  a very  poor  quality,  and 
flimsy  concrete  stiffened  with  light  metal  passed  as  reenforced  con- 
crete. Cinder  concrete  was  used  extensively  for  floors  and  elsewhere, 
and  was  of  a very  inferior  grade.  Much  of  it  was  high  in  sulphides, 
which  had  a deleterious  effect  on  the  embedded  material,  especially 
in  floors  where  slight  cracks  permitted  air  and  moisture  to  come  fn 
contact  with  these  sulphides  and  the  metal.  For  a proper  earthquake- 
proof  structure,  everything — the  design,  the  materials  used,  and  the 
workmanship — must  be  first-class.  Most  of  the  failures  resulted 
from  bad  design,  poor  workmanship,  and  poor  materials.  If  reen- 
forced concrete  of  the  quality  described  could  give  such  satisfactory 
results  in  meeting  the  extraordinary  conditions  of  the  San  Francisco 
earthquake  and  fire,  it  is  evident  that  much  greater  satisfaction  would 
have  been  given  by  the  use  of  first-class  material. 

The  causes  of  the  failures  in  San  Francisco  may  be  summarized 
as  follows: 

1.  The  effort  on  the  part  of  those  qualified  to  design  and  advise  on 
building  construction  to  meet  the  owners’  demands  by  planning 
structures  so  that  they  can  be  erected  for  the  least  possible  cost,  a 
practice  which  tends  to  a departure  from  the  principles  of  correct 
design,  the  result  being  a structure  that  will  carry  ordinary  loads, 
but  that  fails  when  subjected  to  unusual  conditions.  Such  was  the 
case  at  Stanford  University,  where  the  poorly  constructed  stone- 
veneered  buildings  met  ordinary  conditions,  but  failed  in  the  earth- 
quake ; while  the  more  substantial  structures,  like  the  dormitories — 
one  of  reenforced  concrete  and  the  other  of  solid  stone  masonry — 
survived. 

2.  Actually  dishonest  design  and  construction. 


OBSTACLES  TO  RECONSTRUCTION  OF  SAN  FRANCISCO.  59 

The  following  requirements  should  be  adhered  to  in  structures  for 
earthquake  countries : 

1.  Location  on  or  near  the  fault  should  be  avoided. 

2.  Foundations  and  superstructures  should  be  so  built  that  they 
will  move  as  a unit. 

3.  Wooden  structures  should  be  rather  heavily  framed,  with  con- 
tinuity in  the  vertical  members,  adequate  diagonal  bracing,  and  sub- 
stantial foundations. 

4.  Steel  structures  should  rest  upon  an  adequate  foundation  and 
be  thoroughly  braced  diagonally.  This  feature  is  a most  important 
one,  as  rigidity  is  absolutely  essential. 

5.  Brickwork  and  stonework  should  be  thoroughly  bonded  with 
full  header  courses  laid  in  Portland-cement  mortar. 

6.  Masonry  should  be  thoroughly  tied  to  the  steel  or  other  framing 
members. 

7.  Buildings  should  have  no  unnecessary  material  in  their  super- 
structures, and  heavy  ornamentation  should  be  omitted. 

8.  Flimsy  floors  and  partitions  should  be  avoided;  reenforced  con- 
crete is  an  excellent  material  for  both. 

Professor  Omori,  chairman  of  the  Japanese  earthquake  commis- 
sion, and  other  earthquake  authorities,  have  stated  that  great  earth- 
quakes are  followed  by  a settled  condition  in  the  earth’s  surface  and 
that  there  is  an  interval  of  fifty  or  one  hundred  years  during  which 
no  earthquakes  occur.  The  general  fear  which  prevailed  during  the 
first  days  following  the  earthquake  has  been  quieted  by  these  assur- 
ances, which  have  also  created  a feeling  of  security  that  has  led  to  a 
relaxation  of  the  precautions  necessary  in  the  work  of  reconstruction. 
The  lessons  taught  by  the  great  calamities  such  as  have  befallen  San 
Francisco,  Baltimore,  Chicago,  and  other  cities  are  not  regarded.  It 
is  very  probable  that  the  new  San  Francisco  to  rise  on  the  ruins  will 
be,  to  a large  extent,  a duplicate  of  the  former  city  in  defects  of 
construction. 

OBSTACLES  TO  RECONSTRUCTION  OF  SAN  FRANCISCO. 

The  actual  loss  by  fire  in  San  Francisco  was  much  greater  than  in 
the  Baltimore  fire,  for  the  reason  that  many  insurance  companies 
have  taken  advantage  of  the  earthquake  clause  in  the  policies  and 
failed  to  pay  their  claims,  while  others  without  the  requisite  funds 
were  unable  to  pay  the  large  claims  in  full.  This  failure  to  pay  a 
very  considerable  percentage  of  the  fire  losses  and  the  delay  in 
adjusting  them  have  proved  serious  setbacks  in  the  progress  of 
reconstruction. 

The  new  building  code  is  also  operating  against  the  best  interests 
of  the  city.  The  arbitrary  classification  of  buildings  based  on  the 


60 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


type  of  construction  is  one  which  will  result  in  more  harm  than  good. 
Those  interested  in  its  preparation  directed  their  attention  princi- 
pally to  office  and  other  large  buildings,  apparently  not  realizing 
that  the  greater  proportion  of  reconstruction  will  consist  of  small 
three  or  four  story  buildings.  The  fact  that  a structure  is  built  of 
steel  and  fireproofed  does  not  make  it  superior  to  those  representing 
other  types  of  construction,  for  poor  materials  and  workmanship 
may  produce  inferior  quality,  whatever  the  type. 

The  proposed  code  discriminates  against  reenforced-concrete  build- 
ings in  designating  them  as  class  B structures.  While  not  inten- 
tional, this  conveys  the  impression  that  such  buildings  are  next  in 
order  of  superiority  to  structures  of  class  A.  Class  A should  embrace 
buildings  so  well  designed  and  constructed  of  such  first-class  materials 
that  they  afford  the  maximum  resistance  to  fire,  and  should  repre- 
sent the  best  method  of  fireproof  construction  regardless  of  type. 

That  there  was  only  one  reenforced-concrete  building  of  the  mod- 
ern type  in  San  Francisco  was  due  in  part  to  the  opposition  of  the 
labor  unions.  The  exorbitant  demands  for  wages,  coupled  with  the 
high  cost  of  materials,  have  proved  a serious  handicap.  The  cost  of 
all  construction  work  is  excessive  at  the  present  time,  and  business  in- 
terests will  suffer  from  the  shrinkage  in  value  which  will  follow  the 
fall  in  price  of  labor  and  materials.  This  policy  of  the  labor  organi- 
zations is  materially  interfering  with  and  checking  the  work  of  recon- 
struction. 

In  addition  to  these  labor  difficulties,  the  questions  of  widening 
and  extending  old  streets  and  opening  new  ones,  for  the  purpose  of 
carrying  out  the  plans  for  the  new  and  greater  city,  are  still  unde- 
cided, and  most  of  the  business  men  are  unwilling  to  begin  the  work 
of  reconstruction  until  these  points  are  settled. 

STATISTICS  ANTD  GENERAL  INFORMATION. 

The  defects  of  construction  which  are  so  strongly  condemned  by 
reason  of  the  failure  of  the  structures  were  no  worse  than  those  gen- 
erally existing  throughout  the  United  States.  The  same  defects  are 
common,  and  it  is  evident  that  the  same  result  would  follow  an  earth- 
quake of  equal  intensity  in  another  part  of  the  country.  A moment’s 
consideration  will  show  that  the  loss  of  life  and  property  in  New 
York,  for  example,  under  similar  conditions,  would  be  enormous. 
The  damage  to  property  in  San  Francisco  is  estimated  at  $250,000,000, 
but  this  sum,  large  as  it  is,  is  exceeded  by  the  total  annual  expendi- 
tures for  new  construction  in  New  York. 

The  loss  of  life  from  earthquakes  is  usually  very  great.  That  it 
did  not  exceed  500  in  San  Francisco  is  explained  by  the  fact  that  at 
the  time  of  its  occurrence,  during  the  early  hours  of  the  morning, 


STATISTICS  AND  GENERAL  INFORMATION. 


61 


most  of  the  inhabitants  were  in  houses,  90  per  cent  of  which  were  of 
frame.  Structures  of  this  type  withstood  the  earthquake  shock  par- 
ticularly well,  which  accounts  for  the  minimum  loss  of  life.  Had 
the  earthquake  occurred  four  or  five  hours  later,  when  the  people 
were  performing  their  daily  tasks,  in  offices,  schools,  etc.,  or  on  the 
streets,  the  loss  of  life  must  have  been  very  great.  The  writer  saw 
a view  of  a drove  of  cattle  buried  under  the  ruins  of  a fallen  wall 
while  passing  through  Mission  street,  which  graphically  told  the 
story  of  what  might  have  occurred  had  the  shock  come  later  in  the 
day.  Although  the  loss  of  life  was  small,  more  than  200,000  people 
were  rendered  homeless  and  dependent  on  the  authorities  for  even 
the  necessaries  of  life. 

In  three  days  the  tremendous  area  of  more  than  2,593  acres  was 
burned,  destroying  entirely  490  city  blocks  and  in  part  32  blocks. 
(See  Pis.  LIY-LVII.)  Of  this  area,  314  acres  constituted  the  con- 
gested district,  on  which  there  was  $250,000,000  insurance,  probably 
representing  a value  of  at  least  $500,000,000. 

In  the  Baltimore  fire  (February,  1904)  1,343  buildings  were  de- 
stroyed, having  an  assessed  value  of  $12,908,300.  In  two  years  these 
burned  buildings  were  replaced  by  570  buildings,  whose  assessed 
value  is  $20,000,000.  These  new  buildings  are  larger  than  the  old, 
and  the  widening  of  the  streets  has  eliminated  700  building  lots.  It 
is  expected  that  when  the  reconstruction  within  the  burned  district 
is  complete  there  will  be  fewer  than  800  buildings,  of  which  the 
assessed  value  will  be  fully  $25,000,000.  It  is  therefore  quite  reason- 
able to  suppose  that  the  assessed  value  of  the  reconstructed  San 
Francisco  will  be  at  least  double  that  at  the  time  of  the  catastrophe. 


THE  EFFECTS  OF  THE  EARTHQUAKE  AND  FIRE 
ON  BUILDINGS,  ENGINEERING  STRUCTURES,  AND 
STRUCTURAL  MATERIALS. 


By  John  Stephen  Sewell. 


INTRODUCTION. 

SCOPE  OF  THE  INVESTIGATION. 

The  following  pages  contain  the  matter  of  a report  dated  July  5, 
1906,  to  Brig.  Gen.  Alexander  Mackenzie,  Chief  of  Engineers,  United 
States  Army,  of  an  inspection  made  by  me  of  the  ruins  of  San 
Francisco,  in  accordance  with  Special  Orders  No.  97,  dated  War 
Department,  Washington,  April  23,  1906. 

I arrived  in  San  Francisco  on  the  morning  of  May  8,  1906,  and 
remained  until  the  night  of  May  19.  My  orders  directed  me  to  inves- 
tigate the  effect  of  the  fire  and  earthquake  on  buildings  and  engineer- 
ing structures  in  the  territory  affected  by  the  earthquake,  and  author- 
ized me  to  visit  such  points  in  addition  to  San  Francisco  as  it  might 
be  necessary  to  observe.  As  soon  as  possible  after  my  arrival,  I 
called  on  the  various  military  and  civil  authorities,  and  procured 
from  the  latter  permits  authorizing  me  to  enter  and  inspect  the  dam- 
aged structures. 

It  appeared  that  in  the  territory  affected  by  the  earthquake,  in 
addition  to  buildings  of  various  types,  there  were  the  works  of  the 
Spring  Valley  Water  Company  and  fortifications,  light-houses,,  and 
railroad  structures.  Some  rumors  of  collapsed  tunnels  on  the  coast 
division  of  the  Southern  Pacific  Railroad  had  been  circulated  in  the 
East  before  I left  Washington.  I found  on  inquiry,  however,  that 
no  tunnels  had  collapsed,  and  whatever  damage  had  been  done,  except 
to  buildings  along  the  line,  had  been  wholly  or  partly  repaired  before 
I reached  California. 

Inquiry  among  engineers  and  others  competent  to  speak  disclosed 
the  fact  that  the  dams  of  the  Spring  Valley  Water  Company  were 
practically  not  injured  by  the  earthquake.  Considerable  damage  was 
done  to  some  of  their  conduits  and  to  the  pipes  of  the  distribution 
system.  Inquiry  in  reference  to  these  items  disclosed  the  fact  that  a 


63 


SCOPE  OF  INVESTIGATION. 

personal  examination  would  consume  a great  deal  of  time.  It  also 
disclosed  the  fact  that  an  examination  was  in  process  by  competent 
engineers,  and  Major  McKinstry  undertook  to  get  for  me  a report  of 
the  results  of  this  examination.  As  a matter  of  fact,  I have  been 
allowed  to  see  a copy  of  such  a report  made  by  Charles  D.  Marx 
and  Charles  B.  Wing,  which  the  authors  prefer  not  to  have  pub- 
lished as  yet.  However,  certain  essential  facts  as  to  the  condition 
of  dams,  conduits,  etc.  (see  Pis.  IX;  X,  A / XI,  B ),  are  taken  from  it 
and  embodied  further  on  in  my  own  report ; although  the  photographs 
and  certain  other  features  of  the  report  itself,  which  seem  to  be  pecul- 
iarly the  property  of  its  authors,  are  "not  submitted  herewith.  In 
view  of  the  fact  that  the  results  of  the  examination  of  the  waterworks 
were  promised  to  me,  it  seemed  superfluous  for  me  to  visit  the  dams 
and  conduits,  except  as  a matter  of  personal  interest,  and  as  my  time 
was  very  short,  I decided  not  to  do  so. 

The  light-houses  and  fortifications  are  in  charge  of  competent  offi- 
cers, whose  duty  it  is  to  report  the  nature  and  extent  of  the  damage 
done  to  them  by  the  earthquake.  As  an  inspection  of  the  light-houses 
would  have  involved  a great  deal  of  time,  I decided  not  to  attempt 
to  visit  them,  and  made  only  a superficial  examination  of  the  forti- 
fications. 

As  my  own  experience  has  been  mainly  in  the  line  of  fireproof 
buildings,  however,  I made  a very  careful  inspection  of  the  ruins  of 
San  Francisco  itself,  and  also  visited  Oakland  and  Palo  Alto,  with 
a view  to  inspecting  damaged  buildings  at  those  points.  I found,  as 
a result  of  those  trips  and  by  inquiry  among  competent  witnesses, 
that,  with  one  exception,  there  was  no  type  of  building  in  the  affected 
district  which  was  not  well  represented  among  the  buildings  of  San 
Francisco.  The  exception  was  the  concrete  work  at  Leland  Stanford 
Junior  University,  near  Palo  Alto,  to  which  specific  reference  is 
made  on  page  113.  The  greater  part  of  my  time,  for  the  reasons 
above  outlined,  was  spent  within  the  limits  of  San  Francisco  itself, 
and  much  of  it  within  what  had  been  the  congested  district  of  the 
city. 

ACKNOWLEDGMENTS. 

Acknowledgment  is  due  to  Capt.  M.  L.  Walker,  Corps  of  Engineers, 
commanding  officer  at  Fort  Mason,  who  not  only  entertained  me  at 
his  quarters  during  my  stay  in  San  Francisco,  but  rendered  very 
material  assistance  in  the  way  of  transportation  when  needed,  and 
especially  in  placing  at  my  disposal  the  services  of  Private  William  H. 
Hughes,  of  the  First  Battalion  of  Engineers,  a very  efficient  photog- 
rapher, who  accompanied  me  and  took  such  views  as  seemed  desir- 
able for  the  purposes  of  my  report.  I was  also  much  indebted  to 
Maj.  C.  H.  McKinstry,  Corps  of  Engineers,  who  gave  me  much 


64 


THE  SAX  FRANCISCO  EARTHQUAKE  AXD  EIRE. 


valuable  information  that  made  it  possible  to  avoid  useless  expendi- 
ture of  time,  and  who  was  also  of  great  service  in  procuring  for  me 
the  necessary  permits  from  the  local  civil  authorities. 

EXTRACTS  FROM  THE  REPORT  OF  A COMMITTEE  OF  THE  NATIONAL 

BOARD  OF  FIRE  UNDERWRITERS  ON  SAN  FRANCISCO  CONDI- 
TIONS. 

San  Francisco  before  the  earthquake  and  fire  consisted  mainly  of 
frame  and  brick  buildings  of  ordinary  construction.  A few  adobe 
buildings  still  remain,  but  there  were  not  many  of  these.  There 
were  about  45  so-called  fireproof  buildings  in  the  city,  and  a small 
number  of  so-called  slow-burning  buildings,  modeled  more  or  less 
loosely  along  the  lines  of  the  New’ England  mills.  A fair  idea  of  the 
general  nature  of  the  city,  so  far  as  buildings  are  concerned,  is  given 
in  the  following  quotations  from  a report  on  San  Francisco  issued  by 
the  committee  of  twenty  of  the  National  Board  of  Fire  Underwriters 
in  October,  1905 : 

CONFLAGRATION  HAZARD. 

Potential. — In  view  of  the  excessively  large  areas,  great  heights,  numerous 
unprotected  openings,  general  absence  of  fire  breaks  and  stops,  highly  com- 
bustible nature  of  the  buildings,  many  of  which  have  sheathed  walls  and  ceilings, 
frequency  of  light  wells,  and  the  presence  of  interspersed ' frame  buildings,  the 
potential  hazard  is  very  severe. 

Probability  feature. — The  above  features,  combined  with  the  almost  total  lack 
of  sprinklers,  and  absence  of  modern  protective  devices  generally,  numerous 
and  mutually  aggravating  conflagration  breeders,  high  winds  and  compara- 
tively narrow  streets,  make  the  probability  feature  alarmingly  severe. 

Summary. — While  two  of  the  five  sections  into  which  the  congested-value 
district  is  divided  involve  only  a mild  conflagration  hazard  within  their  own 
limits,  they  are  badly  exposed  by  the  others,  in  which  all  the  elements  of  the 
conflagration  hazard  are  present  to  a marked  degree.  Not  only  is  the  hazard 
extreme  within  the  congested-value  district,  but  it  is  augmented  by  the  presence 
of  a compact  surrounding,  great-height,  large-area,  frame-residence  district, 
itself  unmanageable  from  a fire-fighting  standpoint  by  reason  of  adverse  con- 
ditions introduced  by  the  topography.  In  fact,  San  Francisco  has  violated  all 
underwriting  traditions  and  precedents  by  not  burning  up ; that  it  has  not  done 
so  is  largely  due  to  the  vigilance  of  the  fire  department,  which  can  not  be  relied 
upon  indefinitely  to  stave  off  the  inevitable. 

In  another  portion  of  the  same  report  the  following  occurs : 

The  principal  features  affecting  the  conflagration  hazard  in  the  business  sec- 
tion are  bad  exposures,  poor  construction,  lack  of  proper  protective  devices, 
excessive  height  in  nonfireproof  buildings,  large  floor  areas,  and  the  large  per- 
centage of  frame  construction  present. 

The  mixed  dwelling  and  minor  mercantile  section  which  immediately  sur- 
rounds the  congested-value  district,  and  extends  from  it  in  all  directions  with 
more  or  less  uniformity,  is  alarmingly  compact. 

* * * The  security  resulting  from  a combination  of  redwood  and  such 

dampness  as  exists  in  San  Francisco  is  regarded  by  the  national  board  engineers 
as  fancied  merely. 


REPORT  OF  UNDERWRITERS  COMMITTEE. 


65 


In  addition  to  the  frame,  ordinary  joisted  brick,  so-called  fireproof, 
and  mill  buildings,  there  were  in  San  Francisco  four  buildings  of  a 
monumental  type,  so  far  as  weight  of  construction  was  concerned. 
These  were  the  new  city  hall  (PI.  XXXI),  the  new  post-office  build- 
ing (Pis.  XLIII  and  XLIV),  the  United  States  mint  (PI. 
XXXVIII),  and  the  appraisers’  stores,  or  custom-house  (PI. 
XXVIII,  A).  The  few  mill  buildings  which  existed  were  not  of  a 
standard  type,  according  to  the  report  of  the  National  Board  of 
Fire  Underwriters.  The  fireproof  buildings  had  been  erected  in 
accordance  with  the  building  laws  of  San  Francisco,  which  provided 
for  three  principal  types  of  commercial  buildings,  known  as  class  A, 
class  B,  and  class  C. 

The  general  requirements  for  buildings  of  these  classes  and  for  mill 
buildings  are  as  follows: 

BUILDINGS  IN  FIRE  LIMITS. 

Section  96.  Every,  building  hereafter  erected  within  the  fire  limits  shall  be 
constructed  in  accordance  with  the  requirements  of  this  ordinance  for  the  con- 
struction of  buildings  of  either  class  A,  class  B,  or  class  C. 

BUILDINGS  OF  CLASSES  A,  B,  AND  C. 

Section  97.  Class  A,  termed  “ fireproof,”  or  “ skeleton  construction,”  shall 
include  all  buildings  wherein  all  external  and  internal  loads  and  strains  are 
transmitted  from  the  top  of  the  building  to  the  foundation  by  skeleton  or  frame- 
work of  steel,  and  the  beams  or  girders  of  which  are  riveted  to  each  other  at 
their  respective  juncture  joints.  A building  of  this  class  must  be  constructed 
of  noninflammable  material  throughout,  and  all  interior  constructive  metal 
work,  with  the  exception  of  the  framing:  for  elevators  and  staircases,  shall  be 
protected  from  fire  by  brick  or 'terra  cotta  at  least  1|  inches  thick,  or  by  plas- 
tering three-fourths  of  an  inch  thick  applied  to  metal  lath.  The  face  of  the 
plastering  shall  be  li  inches  from  the  metal.  Wood  may  be  used  only  for 
window  and  door  frames,  sashes,  standing  finish,  hand  rails  for  stairs,  and  for 
the  upper  and  under  floors  and  their  necessary  sleepers.  Wood  may  also  be 
used  for  isolated  furring  blocks,  but  this  class  shall  not  permit  the  use  of  laths 
or  furrings  of  wood. 

Class  B.  A building  of  this  class  shall  be  constructed  with  all  its  exterior 
walls  and  piers  of  masonry,  or  of  masonry  and  steel,  and  all  exterior  surfaces 
other  than  masonry  shall  be  covered  with  noninflammable  materials.  All  par- 
titions, furred  walls,  or  other  plastered  surfaces  throughout  shall  be  metal 
lathed.  All  interior  metal  work  shall  be  protected  as  in  class  A,  and  in  addition 
the  floor  and  ceiling  joists,  posts,  roof  boards,  and  partitions  may  be  of  wood  in 
such  places  as  does  not  violate  the  requirements  of  any  section  or  clause  of  this 
ordinance. 

Class  C.  A building  of  this  class  shall  be  constructed  the  same  as  class  B in 
every  respect,  except  as  to  the  requirements  for  interior  lathing. 

Section  98.  Limit  of  height  of  buildings  of  classes  A,  B,  and  C : 

Feet. 


Class  A,  limit  of  height 220 

Class  B,  limit  of  height 100 

Class  C,  limit  of  height 82 


(As  amended  by  Ordinance  1297.) 


66  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

SLOW-BURNING  OR  “ MILL  ” CONSTRUCTION. 

Section  99.  A building  of  the  slow-burning  or  “ mill  ” construction  type  is  a 
building  whose  outside  walls  are  built  of  masonry,  concentrated  in  piers  or 
buttresses,  between  which  is  a thin  wall  containing  the  door  and  window  open- 
ings, and  whose  floors  and  roof  are  constructed  of  heavy  timbers,  covered  with 
plank  of  a suitable  thickness ; the  girders  being  supported  between  the  walls 
by  posts. 

SOME  FEATURES  OE  THE  EARTHQUAKE  AND  EIRE. 

AMOUNT  OF  DESTRUCTION  DUE  TO  THE  EARTHQUAKE  AND  FIRE, 

RESPECTIVELY. 

Within  the  burned  area  all  frame  buildings  and  practically  all 
buildings  with  timber  floors  were  totally  destroyed,  with  all  their 
contents.  This  classification  includes  mill  buildings  and  those  of 
every  other  type  in  which  the  floor  construction  is  combustible. 
Practically  all  the  so-called  fireproof  buildings  were  gutted,  and 
their  contents  were  a total  loss.  The  average  loss  on  the  buildings  of 
class  A was,  in  my  judgment,  considerably  in  excess  of  the  average 
loss  on  the  “ fireproof  ” buildings  in  Baltimore.  This  statement  can 
not  be  made  with  absolute  positiveness,  however,  in  the  absence  of  a 
detailed  estimate  of  the  cost  of  repairing  each  building,  which  I had 
not  time  to  make.  I am  quite  sure,  however,  that  the  damage  in  San 
Francisco  was  greater  than  it  was  in  Baltimore. 

From  what  was  left  of  the  ruins  themselves,  and  from  the  testi- 
mony of  competent  observers,  including  engineer  officers  who  were 
ordered  into  the  business  district  of  San  Francisco  immediately  after 
the  earthquake  and  before  the  fire  had  destroyed  the  evidences  of 
earthquake  damage,  I think  it  is  quite  certain  that  the  earthquake 
damage  was  extensive  and  severe.  There  were  no  available  data  on 
which  to  base  an  accurate  estimate,  but  I formed  a general  impression 
that  the  damage  done  by  the  earthquake  alone  was  at  least  as  great 
as  10  per  cent  of  the  total  damage  by  fire  and  earthquake  combined. 
The  damage  from  the  earthquake,  however,  was  localized  in  a re- 
markable degree.  In  places  a group  of  buildings  were  almost  totally 
destroyed,  and  buildings  almost  in  contact  with  them  on  all  sides 
escaped  practically  without  damage,  although  I feel  quite  sure  that 
many  of  the  wrecked  buildings  were  superior  in  every  way  to  their 
neighbors  which  escaped.  Owing  to  the  remarkable  variation  in  the 
intensity  of  the  shock  from  point  to  point,  thus  demonstrated,  the 
measure  of  damage  done  to  an  individual  building  is  by  no  means  a 
measure  of  the  excellency  or  inferiority  of  its  construction.  Some 
specific  evidence  on  this  point  is  presented  elsewhere  in  this  paper. 

FIRE-FIGHTING  OPERATIONS— THE  USE  OF  DYNAMITE. 

The  fire,  of  course,  completed  the  work  begun  by  the  earthquake. 
(See  Pis.  LIV-LVII.)  The  interruption  of  the  water  supply,  due 


USE  OF  DYNAMITE. 


67 


to  the  breaking  of  the  conduits  and  mains,  left  the  fire  practically  in 
control  of  the  situation.  Some  attempts  were  made  to  stop  its 
progress  with  dynamite,  but  from  what  evidence  I was  able  to  obtain 
I doubt  very  much  whether  a great  deal  was  accomplished  by  this 
means.  It  is  probable  that  at  one  or  two  points  where  the  fire  had 
become  much  less  fierce  its  progress  was  entirely  stopped  by  the  use 
of  dynamite,  but  even  this  much  is  not  certain.  I am  personally  of 
the  opinion  that  dynamite  might  be  used  so  as  to  check  the  progress 
of  a conflagration,  but  it  has  never  been  properly  applied  to  that 
purpose  as  yet.  It  seems  probable  that  if  a strip  of  property,  a whole 
city  block  in  depth,  extending  across  the  entire  front  of  the  fire,  were 
selected  sufficiently  far  in  advance  to  enable  it  to  be  completely  razed 
by  dynamite  before  the  fire  reached  it  it  would  prove  an  effectual 
barrier,  especially  if  there  were  water  available  to  keep  the  ruins 
thoroughly  wet.  In  the  absence  of  the  water  the  only  way  to  make 
sure  of  the  result  avouIcI  be  to  have  an  enormous  number  of  men 
ready,  as  soon  as  the  buildings  were  demolished,  to  move  the  debris 
to  the  side  nearest  to  the  approaching  fire.  It  is  probable  that  the 
ruins  would  be  set  on  fire  by  the  dynamite  itself,  but  with  a suffi- 
cient number  of  men,  properly  handled,  the  amount  of  combustible 
matter  along  the  side  next  to  unburned  property  might  be  so  mate- 
rially reduced  that  the  fire  would  not  be  able  to  cross  the  gap.  I 
rather  think  that  unless  such  heroic  measures  are  applied  the  use  of 
dynamite  is  just  as  likely  to  do  harm  as  good  in  resisting  the  advance 
of  a conflagration.  It  will  readily  occur  to  anyone  at  all  familiar 
with  such  things  that  to  get  together  the  requisite  number  of  men 
and  properly  direct  their  work  would  require  full  military  control 
of  the  situation;  otherwise  the  measures  described,  while  not  im- 
possible, would  hardly  be  practicable. 

One  or  two  attempts  were  made,  apparently  with  not  a great  deal 
of  judgment,  to  dynamite  steel-frame  buildings  that  were  on  fire.  I 
understand  that  the  explosive  was  simply  placed  in  the  basement 
loose,  practically  without  any  tamping,  and  detonated.  The  only 
result  was  to  knock  a few  basement  columns  off  their  foundations  and 
bring  down  a portion  of  the  floor  construction  above.  I doubt 
whether  any  good  results  could  be  obtained  by  trying  to  dynamite  a 
steel-frame  building  as  a means  of  stopping  the  advance  of  a fire. 
If,  in  a strip  of  property  such  as  that  described  above,  any  steel-frame 
buildings  exist,  especially  if  the  frames  are  protected  with  any  sort 
of  fireproofing,  it  is  probable  that  more  good  would  result  from 
allowing  them  to  stand,  while  dynamiting  their  combustible 
neighbors. 

It  would  be  practically  impossible  in  the  time  available  to  demolish 
a steel  frame  so  completely  that  all  of  the  combustible  debris  could 
be  properly  handled.  It  would  burn  more  freely  and  more  disas-* 


68 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


trously  after  dynamiting  than  if  the  building  were  left  intact.  A 
good  plan  in  such  a case  would  be  to  remove  all  the  combustible 
contents  of  the  building  before  the  fire  reached  it,  throwing  them  out, 
if  no  other  course  were  open,  on  the  side  next  to  the  advancing  con- 
flagration. Under  such  circumstances  the  average  fireproof  building, 
while  it  might  be  ruined  itself,  would  probably  act  as  a barrier  to  the 
spread  of  the  flames  beyond  it,  although,  of  course,  it  could  not  pre- 
vent the  fire  from  working  around  the  sides  if  neighboring  com- 
bustible buildings  were  not  removed. 

A certain  amount  of  damage  in  addition  to  that  caused  by  the  fire 
and  earthquake  was  done  in  San  Francisco  by  the  dynamite  used  to 
blow  down  dangerous  walls.  More  specific  data  on  this  point  are 
presented  in  the  detailed  descriptions. 

TEMPERATURE  OF  THE  BALTIMORE  AND  SAN  FRANCISCO  FIRES. 

The  apparently  more  complete  destruction  by  fire  at  San  Francisco 
than  at  Baltimore  immediately  raises  questions  as  to  the  probable 
temperature  of  the  San  Francisco  fire.  I noted  everything  coming 
under  my  observation  which  would  seem  to  give  an  idea  as  to  the 
probable  temperature  prevailing,  and  I am  personally  of  the  opinion 
that  the  San  Francisco  fire  was  appreciably  hotter  than  that  at  Balti- 
more. Thus,  in  places  which  had  been  occupied  by  hardware  stores  I 
saw  kegfuls  of  nails  with  the  wood  all  burned  away,  but  with  the  nails 
still  standing  up  in  a compact  mass,  retaining  the  shape  of  the  keg, 
owing  to  the  fact  that  they  had  been  partially  welded  together.  In 
other  places  kegfuls  of  nails  which  had  evidently  fallen  at  least  one 
story,  and  possibly  several  stories,  into  the  basement  of  an  adjoining 
building,  had  nevertheless  retained  the  form  and  size  of  the  keg, 
although  some  of  the  nails  were  loosened.  I also  saw  a number  of 
cast-iron  radiators  that  were  partially  melted  and  some  cast-iron 
soil-pipe  fittings  that  had  been  melted  to  such  an  extent  that  it  was 
not  possible  to  tell  what  sort  of  fittings  they  had  been.  In  some 
cast-iron  columns  which  had  been  softened  and  broken  in  the  fire  the 
raw  edges  of  the  break  were  appreciably  rounded  and  blunted,  due 
to  the  incipient  fusion  of  the  metal.'  In  the  basement  of  an  iron 
warehouse  I saw  a number  of  racks  of  steel  bars  which  had  apparently 
been  precipitated  from  the  first  floor  and  which  were  to  a consider- 
able extent  welded  together.  The  weld  was  not  perfect,  of  course,  but 
at  some  of  the  points  where  the  welds  occurred  it  would  have  been 
impossible  to  separate  the  bars  without  considerable  damage. 

Glass  of  all  kinds  melted  and  ran  freely.  Lead  sash  weights  melted 
and  ran  out  of  the  window  boxes  before  the  timber  of  the  boxes  was 
entirely  consumed.  Several  witnesses,  among  them  an  engineer  offi- 
cer, told  me  that  they  had  observed  this  phenomenon  in  a number  of 
places.  The  sheet-metal  cases  of  typewriters  and  similar  articles  of 


TEMPERATURES  OF  THIS  AND  BALTIMORE  FIRES.  69 

sheet  metal,  though  they  showed  no  evidence  of  melting,  had  been 
almost  completely  burned  up,  so  that  they  were  full  of  holes,  and  the 
metal  itself  presented  the  same  appearance  as  iron  that  had  been 
burned  in  a blacksmith’s  forge.  In  the  warehouse  of  the  Waterhouse 
& Lester  Company,  on  Howard  street,  some  racks  of  steel  bars  were 
precipitated  into  the  basement  when  the  building  collapsed.  These 
bars  were  partially  welded  together  by  heat.  (See  also  PL  LI,  B.) 
In  the  ruins  of  glassware  and  china  stores  the  glass,  as  a rule,  was 
completely  melted,  and  many  articles  of  porcelain  ware  had  become 
softened  and  distorted  in  all  manner  of  shapes,  indicating  a high 
temperature,  as  porcelain  is  made  of  very  refractory  material. 

All  things  considered,  I am  inclined  to  think  that  temperatures 
considerably  in  excess  of  2,000°  F.  were  not  at  all  uncommon  in  the 
San  Francisco  fire,  although  there  were  manifestly,  in  the  burned 
area,  places  where  no  such  temperature  was  reached.  Very  few  office 
buildings  were  subjected  to  such  intense  heat,  except  here  and  there 
in  individual  rooms,  where  there  was  evidence  of  the  storage  of  rec- 
ords or  other  combustible  matter  in  large  quantities;  but  the  depart- 
ment stores,  dry  goods  stores,  and  other  buildings  of  mercantile 
occupancy  evidently  suffered  from  temperatures  at  least  as  high  as 
2,000°  F.  In  mercantile  buildings  these  high  temperatures  seemed  to 
be  the  rule  and  not  the  exception. 

EARTHQUAKE-  AND  FIRE-RESISTIKG  QUALITIES  OF 
STRUCTURES  AND  STRUCTURAL  MATERIALS. 

EFFECT  OF  FIRE  ON  GOVERNMENT  AND  “CLASS  A”  COMMERCIAL 

BUILDINGS. 

So  far  as  resistance  to  the  fire  is  concerned,  the  only  buildings  that 
presented  anything  of  interest  were  naturally  the  monumental  public 
buildings  and  the  commercial  fireproof  buildings  of  the  better  class; 
that  is,  practically  of  class  A.  The  fire  did  not  succeed  in  entering 
the  mint  nor  the  appraisers’  stores.  It  got  into  the  upper  story  of 
the  new  post-office  building  at  one  corner,  and  cleaned  out  a court 
room  and  its  adjoining  offices;  but  it  was  held  at  this  point,  and  the 
post-office  building  itself  was  not  involved  in  a fierce  conflagration 
such  as  that  which  ruined  many  of  the  commercial  buildings.  The 
fire  got  into  the  new  city  hall,  and  succeeded  in  wrecking  the  portion 
which  was  not  ruined  by  the  earthquake. 

VAULTS  AND  SAFES. 

In  many  of  the  office  buildings  in  San  Francisco  suites  of  offices 
were  equipped  with  vaults,  some  of  which  were  fairly  capacious  and 
provided  with  doors  of  more  or  less  efficient  appearance,  a number  of 
them  having  the  ordinary  vestibule,  with  both  inner  and  outer  doors. 
Where  the  interior  partitions  of  the  building  consisted  of  metal 
7171— Bull.  324—07 6 


7 0 THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

furring,  lathing,  and  plaster,  the  walls  of  the  vaults  were  likewise  of 
these  materials.  Where  the  interior  partitions  consisted  of  hollow 
tile,  the  walls  of  the  vaults  were  of  hollow  tile  also.  Although  I 
examined  a great  many,  I did  not  see  a single  vault  partitioned  off 
either  with  metal  lathing  and  plaster  or  with  hollow  tiles  that  pre- 
served its  contents.  I was  informed  by  some  gentlemen,  who  were 
apparently  connected  with  the  Spring  Valley  Water  Company,  that 
on  the  top  floor  of  their  building  a vault  walled  off  with  hollow  tiles 
had  protected  its  contents,  but  that  the  corner  of  the  building  in 
which  it  was  situated  had  not  been  completely  gutted,  so  that  the 
vault  did  not  receive  a severe  test. 

In  the  Baltimore  fire  there  were  a number  of  vaults  walled  off  with 
hollow  tiles,  and  all  that  I happened  to  see  during  my  inspection  of 
the  ruins  in  Baltimore  had  failed.  The  same  thing  was  in  evidence 
everywhere  in  San  Francisco,  and  it  is  my  opinion  that  this  result 
could  have  been  predicted  with  absolute  certainty  at  the  time  these 
vaults  were  built,  from  data  then  available.  To  all  external  appear- 
ances, no  doubt,  the  vaults  looked  like  secure  places  in  which  to 
keep  valuables;  as  a matter  of  fact,  they  were  the  flimsiest  kind  of 
shells,  not  capable  of  resisting  any  sort  of  determined  attack  from 
either  fire  or  burglars.  The  tenant  would  have  been  better  off  with- 
out the  vault,  for  in  that  case  he  would  probably  have  carried  his 
papers  to  some  other  point  where  they  would  have  had  a better 
chance  to  escape  the  fire. 

The  only  vaults  I saw  that  came  through  a really  fierce  fire  without 
damage  were  those  built  of  brickwork  (PI.  LII,  A).  Even  these 
vaults  did  not  always  protect  their  contents,  however.  I saw  a num- 
ber of  them  opened  in  which  the  contents  had  been  totally  destroyed. 
As  they  seemed  to  be  fairly  good  vaults,  this  result  was  a matter  of 
more  than  ordinary  interest.  I therefore  carefully  examined  a num- 
ber of  them  and  discovered  that  the  fire  had  gained  access  through 
cracks  due  to  settling,  or  to  the  earthquake,  or  else  through  unfilled 
joints,  due  to  poor  workmanship  in  the  original  construction  of  the 
vault.  It  appeared  that  probably  the  contents  of  the  building  were 
burning  fiercely  around  the  vault  before  the  floor  above  had  burned 
out  or  collapsed,  so  as  to  give  full  vent  to  the  gases  of  combustion. 
Some  pressure  must  have  been  generated  by  the  great  heat  thus 
confined,  and  under  this  pressure  the  incandescent  gases  resulting 
from  the  fire  found  their  way  through  the  smallest  and  most  tor- 
tuous passages  in  the  brickwork.  In  several  cases  it  was  apparent 
that  the  contents  had  probably  been  ignited  by  a small  tongue  of 
flame  (probably  not  thicker  than  a lead  pencil)  penetrating  into  the 
vault  as  a result  of  such  conditions. 

A few  vaults  failed  owing  to  the  fact  that  the  outer  door  warped 
and  pulled  away  from  the  frame.  Whether  this  warping  could  have 


BEHAVIOR  OF  STRUCTURAL  MEMBERS  AND  MATERIALS.  71 


been  prevented  with  an  adequate  number  of  bolts  I do  not  know,  but 
in  an  important  vault  it  would  seem  worth  while  to  have  the  outer 
door  at  least  filled  in  the  same  manner  as  the  door  of  a fireproof  safe. 
If  it  were  built  in  this  way  it  would  probably  not  warp — at  least 
not  enough  to  let  the  fire  in. 

To  judge  from  the  safes  which  I saw  opened,  very  nearly  three- 
fourths  of  the  safes  in  the  San  Francisco  fire  failed  to  protect  their 
contents  (Pl.  LII,  B ),  and  as  a result  the  loss  of  valuable  papers 
and  records  must  have  been  very  extensive. 

BEHAVIOR  OF  STRUCTURAL  MEMBERS  AND  MATERIALS. 

The  commercial  fireproof  buildings  in  San  Francisco,  in  my  judg- 
ment, suffered  considerably  more  damage  than  corresponding  build- 
ings in  the  Baltimore  conflagration.  In  the  San  Francisco  fire,  for 
the  first  time,  the  collapse  of  protected  steel  frames,  due  to  the 
destruction  of  the  fireproof  covering  at  a comparatively  early  stage 
in  the  fire,  was  a matter  of  common  occurrence.  Practically  all  of 
the  floor  construction  in  fireproof  buildings  in  San  Francisco  consisted 
either  of  hollow  terra-cotta  flat  arches  or  of  reenforced-concrete  slabs, 
carried  on  steel  floor  beams.  In  a few  buildings  steel  columns  and 
girders  were  used,  with  reenforced-concrete  beams  and  slabs  covering 
the  space  between  the  girders.  Steel  girders  were  more  generally 
protected  with  metal  lathing  and  plaster,  or  with  solid  concrete  fill- 
ing, than  with  anything  else,  but  terra-cotta  covering  was  also  used 
to  a considerable  extent.  The  lower  flanges  of  beams  were  in  some 
buildings  unprotected;  in  others  they  were  covered  with  metal  lath- 
ing and  plaster;  and  in  still  others  (a  rather  general  practice),  there 
was  a ceiling  composed  of  light  furring  angles  and  metal  lathing, 
fastened  below  the  floor  construction  and  plastered.  Most  of  the  steel 
beams  and  girders  in  the  floor  construction  had  no  other  protection 
for  their  lower  flanges  than  this  furred  ceiling,  even  where  the  webs 
were  protected  by  a solid  concrete  filling. 

Columns  were  generally  protected  in  one  of  three  different  ways, 
as  follows: 

1.  With  hollow  tiles  adapted  to  either  a circular  or  square  section, 
the  webs  being  about  five-eighths  of  an  inch  thick,  and  the  total 
thickness  of  the  tile,  including  webs  and  hollow  space  within,  being 
about  2J  or  3 inches.  The  tiles  were  from  12  to  18  inches  in  length 
and  about  12  or  15  inches  wide. 

2.  With  metal  lathing  and  plaster  surrounding  the  column,  so  as 
to  leave  an  air  space  of  about  1 or  1^  inches. 

3.  With  a solid  covering  of  concrete  from  2 to  4 inches  thick. 

In  addition  to  this  protection  the  columns  in  the  walls  were  gener- 
ally covered  with  4 inches  of  brickwork,  and  in  one  building  there  was 
a double  covering  of  metal  lathing  around  isolated  columns,  the 


72  THE  SAN  EEANCISCO  EARTHQUAKE  AND  FIRE. 

inner  covering  having  one  coat  of  plaster  applied  and  the  outer 
covering  having  the  full  two  or  three  coats  required  for  the  finishing, 
as  the  case  might  be. 

In  a general  way,  practically  none  of  the  column  protection  in 
San  Francisco,  except  the  4-inch  brick  covering,  was  adequate.  The 
coverings  of  terra  cotta  and  of  metal  lathing  and  plaster  failed  abso- 
lutely. Although  there  were  a great  many  individual  columns  pro- 
tected with  other  coverings  which  suffered  only  small  damage,  the  num- 
ber in  which  the  protection  completely  failed  was  so  great  that  the 
statement  is  entirely  justified  that  practically  all  the  coverings  were 
wholly  inadequate  to  resist  any  real  fire  test.  The  wall  columns 
covered  with  4 inches  of  brickwork  were,  except  in  one  building, 
fairly  well  protected,  so  far  as  I was  able  to  determine.  None  of  the 
columns  covered  with  cinder  concrete  suffered  any  serious  damage, 
but  there  were  not  many  columns  protected  in  this  way.  Of  the  three 
buildings  in  which  I particularly  noticed  such  covering,  two  had 
evidently  not  experienced  any  great  heat.  In  the  third  a column 
covered  with  4 inches  of  cinder  concrete  had  undoubtedly  been  sub- 
jected to  a heat  that  was  very  intense.  The  concrete  covering  was 
seriously  damaged;  the  column,  however,  had  not  suffered.  This 
case  is  described  on  page  79. 

Interior  partitions  in  San  Francisco  were  built  almost  entirely  of 
hollow  tiles  similar  to  those  used  for  making  square  coverings  on 
columns,  or  else  of  light  metal  studs  covered  with  metal  lathing  and 
plaster.  A few  were  built  of  brickwork.  In  a general  way  it  may  be 
said  that  practically  all  the  interior  partitions  that  were  not  built  of 
brickwork  were  a total  loss,  being  absolutely  inadequate.  In  my 
judgment,  the  burning  of  the  contents  of  a single  well-filled  office 
room  would  have  developed  in  the  majority  of  buildings  enough  heat 
to  get  through  the  surrounding  partitions. 

The  furred  ceilings  already  described  were  also  very  largely  a loss. 
In  buildings  that  had  been  occupied  for  ordinary  office  purposes, 
probably  not  more  than  20  per  cent  of  the  furred  ceilings  absolutely 
came  down ; the  remaining  80  per  cent  stayed  in  place,  with  complete 
loss  of  the  plaster,  the  metal  furring  and  lathing,  however,  being  in 
shape  to  use  again  with  only  minor  repairs.  But  wherever  the 
amount  of  combustible  matter  was  evidently  greater  than  that  ordi- 
narily found  in  offices,  the  entire  furred  ceiling — metal  lathing,  fur- 
ring strips,  and  all — came  down  bodily  and  was  a total  loss. 

So  far  as  I was  able  to  determine,  the  earthquake  did  not  cause  the 
collapse  of  any  of  the  floor  construction  or  partitions  in  any  of  the 
fireproof  buildings,  but  it  must  have  shaken  a good  many  of  the 
partitions  badly,  so  that  their  destruction  by  fire  was  rendered  some- 
what more  easy.  The  earthquake  damage,  however,  only  hastened 
the  result.  Partitions  of  the  kind  that  were  used  in  San  Francisco 


BEHAVIOR  OF  STRUCTURAL  MEMBERS  AND  MATERIALS. 


73 


are  not  fireproof,  and  a very  hot  fire  will  invariably  destroy  them, 
notwithstanding  the  fact  that  they  are  made  of  noncombustible 
material.  I had  rather  expected  to  find  that  some  damage  had  been 
done  by  the  earthquake  to  floors  made  of  hollow  tiles  or  brick  arches. 
That  no  such  damage  occurred  was  a matter  of  some  surprise,  and 
indicates  that  the  vertical  component  of  the  undulation  was  not  very 
great.  It  is  probable  that  the  earthquake  caused  some  cracks  to 
appear  in  the  floors,  but  I did  not  see  any  which  could  with  certainty 
be  ascribed  to  this  cause.  It  was  also  a matter  of  some  surprise  that 
some  of  the  partitions  were  not  shaken  down  by  the  earthquake,  con- 
sidering the  ease  with  which  the  fire  destroyed  them. 

So  far  as  fire  damage  was  concerned,  the  floor  systems  in  San  Fran- 
cisco stood  better  than  any  other  portion  of  the  fireproof  buildings, 
although  they  did  not  stand  very  well,  at  that.  The  lower  webs 
came  off  from  the  hollow-tile  floor  arches  in  the  same  way  that  they 
did  aT  Baltimore,  but  to  a very  much  greater  extent.  The  cinder- 
concrete  floor  slabs  in  many  buildings  were  protected  for  a time  by 
the  furred  ceilings  previously  described.  Where  the  ceilings  failed 
at  an  early  stage,  or  where  there  had  been  no  such  ceilings,  the  dam- 
age to  the  concrete  floor  slabs  was  very  apparent.  The  concrete  was 
dehydrated  to  a certain  extent  on  its  lower  surface,  and  in  many  of 
the  slabs  the  reenforcement  had  become  so  hot  that  there  was  a per- 
manent deflection  of  greater  or  less  extent,  accompanied  by  cracks  on 
the  lower  side  in  the  middle  of  the  span. 

Just  how  much  .damage  was  done  by  the  fire  to  cinder-concrete  slabs 
was  a little  difficult  to  determine,  for  the  reason  that  most  of  the  cin- 
der concrete  used  in  San  Francisco  was  evidently  a very  inferior 
article  in  the  first  place.  There  was  no  doubt  in  my  mind,  however, 
that  the  concrete  near  surfaces  which  had  been  exposed,  to  the  fire 
showed  deterioration,  as  compared  with  that  which  had  not  been  ex- 
posed to  the  fire,  although  it  was  all  so  poor  that  there  was  not  much 
room  for  difference  in  quality.  I saw  reenforced-concrete  floor  slabs, 
some  of  cinders  and  some  of  stone,  which  were  on  the  point  of  col- 
lapse from  heat  alone,  although  they  had  not  quite  let  go. 

I also  saw  a number  of  terra-cotta  floor  arches  which  had  totally 
collapsed.  Some  of  these  showed  evidence  of  damage  by  masses  fall- 
ing from  above,  but  in  others  the  collapse  seemed  to  have  been  due  to 
heat  alone. 

Girder  and  beam  protection  was  a little  more  efficient  than  the 
column  coverings,  but  it  was  not  adequate.  Its  weakness  was  not 
fully  developed,  because,  in  many  places  where  the  necessary  heat 
existed,  the  columns  failed  first  and  let  down  the  floors,  so  that  it 
was  not  possible  to  say  how  much  of  the  damage  to  the  floor  members 
was  due  to  heat  alone.  In  a general  way,  however,  it  may  be  said 
that  girder  coverings  of  metal  lath  and  plaster  were  wholly  made- 


74 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  EIRE. 


quate,  those  of  hollow  tiles  suffered  serious  damage,  and  those  of 
solid  concrete  failed  a little  more  commonly  than  they  should, 
although  they  were  the  best  of  all.  Many  girders  that  had  been 
covered  with  metal  lath  and  plaster  were  badly  warped  and  deflected, 
and  some  wholly  collapsed,  from  the  heat  alone.  Many  beams  were 
seriously  deflected  from  the  heating  of  exposed  lower  flanges. 

I was  not  able  to  learn  that  any  serious  damage  had  been  done 
to  column  coverings  by  the  earthquake.  In  some  buildings  columns 
which  had  not  been  exposed  to  much  heat  happened  to  be  standing 
with  their  covering  absolutely  intact,  while  another  column  not  far 
away  in  the  same  story  of  the  building  and  evidently  subjected  to 
an  intense  heat  had  not  only  lost  its  covering,  but  had  itself  been 
practically  destroyed  by  the  fire.  In  no  such  case  was  I able  to  dis- 
cover any  evidence  of  earthquake  damage  in  the  covering  that  was 
intact,  and  there  was  nothing  to  indicate  that  one  column  might 
have  had  its  covering  damaged  by  the  earthquake,  while  its  neighbor 
escaped.  More  detailed  information  relative  to  fire  damage  is  pre- 
sented in  the  discussion  of  the  individual  buildings  (pp.  76-108). 

The  earthquake  did  a great  deal  of  damage,  which  could  easily  be 
differentiated  from  that  due  to  the  fire.  As  a rule  brickwork  in  San 
Francisco  was  laid  in  lime  mortar  or  in  lime  mortar  gaged  with  a 
small  amount  of  Portland  cement.  Wherever  such  masonry  was  sub- 
jected to  serious  earthquake  shocks  it  was  very  badly  shattered. 
Much  of  it  came  down  in  the  ruins,  and  much  of  that  which  remained 
in  place  was  reduced  to  a loose  pile,  without  any  adhesion  between 
the  mortar  and  the  bricks.  The  bricks  in  general  were  more  or  less 
misplaced  even  where  they  did  not  come  down,  and  many  of  them 
were  broken.  Where  brickwork  was  solidly  laid  up  in  good  Portland- 
cement  mortar,  if  the  earthquake  shock  induced  stresses  sufficient  to 
damage  it,  the  damage  generally  appeared  in  the  form  of  well-defined 
cracks,  which  could  have  been  easily  pointed  up,  so  as  to  leave  the 
wall  almost  as  good  as  it  was  before. 

Well-executed  stone  masonry  subjected  to  earthquake  shocks 
showed,  in  many  places,  considerable  slipping  of  the  individual 
stones,  the  adhesion  between  the  stones  and  the  mortar  having  been 
destroyed.  Here  and  there,  where  the  strength  of  the  mortar  ap- 
proached that  of  the  stone,  the  stone  itself  was  badly  shattered  and 
cracked.  Where  the  wall  ran  in  the  direction  in  which  the  undulation 
seems  to  have  been  propagated,  it  generally  showed  an  X-shaped 
crack  (PI.  XXII,  A),  the  legs  of  the  X crossing  the  affected  area  in 
a diagonal  direction.  Where  the  masonry  was  very  good  these  cracks 
were  the  only  apparent  damage,  but  where  it  was  not  so  good  the  indi- 
vidual stones,  bricks,  or  tiles,  as  the  case  might  be,  had  been  loosened 
from  their  beds  and  broken,  so  that  the  entire  mass  was  shattered, 
although  in  many  places  still  standing. 


BEHAVIOR  OF  STRUCTURAL  MEMBERS  AND  MATERIALS.  75 

Iii  steel-frame  buildings  put  up  in  the  ordinary  way,  without  any 
special  bracing,  most  of  the  earthquake  effect  was  localized  in  piers 
between  windows,  as  if  a horizontal  force  had  been  applied  to  the 
floor  above,  tending  to  slide  it  with  reference  to  the  floor  below.  As 
this  effect  occurred  in  both  directions,  the  piers  referred  to  were  gen- 
erally marked  with  X-shaped  cracks,  and  in  addition  the  masonry 
was  apt  to  be  very  much  shattered.  There  seemed  to  be  no  general 
rule  as  to  the  place  where  this  shattering  effect  occurred.  In  some 
buildings  the  piers  in  the  one  or  two  stories  near  the  middle  of  the 
height  of  the  building  seemed  to  have  suffered  the  most ; in  others,  the 
piers  nearer  to  the  roof.  One  tall  building,  which  extended  far  above 
its  neighbors,  was  seriously  damaged  in  practically  every  story  above 
the  neighboring  buildings. 

It  was  apparent  that  in  some  buildings  the  shock  was  so  severe  that 
probably  no  structure,  however  well  built,  could  have  withstood  it 
absolutely  without  damage.  It  was  equally  apparent,  however,  that 
such  great  exhibitions  of  energy  were  confined  to  small  areas,  and 
that  it  would  be  possible  to  put  up  buildings  in  San  Francisco  which 
would  come  through  a similar  earthquake  with  very  little  damage 
except  to  individual  buildings  here  and  there. 

Hollow-tile  work  seemed  to  be  badly  shattered  by  the  earthquake 
in  a great  many  places.  Well-executed  stone  masonry,  as  a rule, 
stood  better  than  brickwork.  Brickwork  built  with  good  hard  bricks, 
laid  in  Portland-cement  mortar,  stood  better  than  that  built  with 
inferior  bricks  or  inferior  mortar. 

Of  all  the  structures  which  were  manifestly  exposed  to  severe  shock 
the  concrete  buildings  at  Palo  Alto  stood  best.  It  would  seem 
to  be  a general  rule  that  increased  tensile  strength,  even  in  a brittle 
material,  greatly  increased  the  resistance  to  earthquake  shock.  The 
height  above  the  ground  at  which  the  damage  was  greatest  appeared 
to  be  largely  a function  of  the  distribution  of  mass  in  the  structure 
itself,  combined  with  the  distribution  of  the  bracing.  If  the  base  of  a 
tall  steel-frame  building  were  subjected  to  a vibration  tending  to  tilt 
it,  manifestly  some  time  would  be  required  to  set  the  upper  part  of  the 
building  in  motion.  As  the  vibration  evidently  occurred  in  both 
directions,  there  would  be  a reversal  of  motion  before  the  upper  part 
of  the  building  had  responded  to  the  first  impulse.  Under  these  cir- 
cumstances there  would  be  established  somewhere  a center  of  oscilla- 
tion, where  very  severe  stresses,  due  to  the  acceleration  of  the  superin- 
cumbent mass,  would  be  largely  concentrated. 

It  might  have  been  supposed  that  most  of  the  destructive  effect  of 
such  action  would  be  manifested  at  the  joints  in  a steel-frame  build- 
ing; but  around  the  joints  are  concentrated  the  ends  of  the  floor 
beams  and  girders,  together  with  the  floor  construction,  and  at  the 
level  of  these  joints  is  the  only  portion  of  the  walls  which  is  per- 


76 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


fectly  solid.  The  shafts  of  the  columns  at  about  midstory  height  are 
therefore  less  efficiently  braced  than  the  portions  on  a level  with  the 
floors.  Moreover,  it  is  probable  that  the  play  in  the  connections  of  the 
steel  work  at  the  floor  level  would  permit  a little  motion  here  with- 
out any  damage,  provided,  in  the  meantime,  the  bracing  at  mid- 
story,  due  to  the  masonry,  is  sufficient  to  preserve  the  structure  from 
collapse ; thus  the  connections  would  escape  without  material  damage. 
As  a matter  of  fact,  some  such  action  seems  to  have  taken  place. 
There  was  very  little  damage  at  the  points  where  the  steel  work  was 
fastened  together ; at  least,  very  little  that  was  apparent. 

The  failure  of  the  masonry  in  the  piers  seems  to  have  prevented 
the  columns  from  being  broken  across  in  the  middle  or  permanently 
deflected.  It  is  an  interesting  speculation  how  near  some  of  the 
unbraced  steel-frame  buildings  wTere  to  total  collapse  under  the 
stresses  above  described.  In  my  judgment  many  of  them  were  a 
little  too  near  for  safety.  I saw  a number  of  field  bolts  or  rivets 
that  I thought  had  probably  been  sheared  by  the  earthquake,  but  as 
to  most  of  them  I was  not  sure  that  they  had  ever  been  in  place.  In 
one  or  two  instances,  however,  the  earthquake  effect  was  indisputable. 

As  it  is  very  difficult  to  discuss  the  earthquake  effect  in  a general 
way,  however,  it  will  be  taken  up  further  in  connection  with  the  sub- 
joined detailed  description  of  the  effect  of  the  earthquake  and  fire 
on  individual  buildings  in  San  Francisco. 

BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 

ACADEMY  OF  SCIENCES  BUILDING. 

The  Academy  of  Sciences  building,  on  Market  street,  was  interest- 
ing because  of  its  interior  construction.  This  building  had  cast- 
iron  concrete-filled  columns  and  Ransome  reenforced-concrete  floor 
construction.  So  far  as  it  was  possible  to  ascertain,  no  damage  was 
done  to  the  reenforced  concrete  or  to  the  columns  by  the  earthquake. 
The  building  was  gutted  and  the  floors  considerably  damaged  by  the 
fire,  but  the  columns  were  not  damaged,  and  on  the  whole  the  build- 
ing stood  very  well.  A very  good  view  of  this  building  was  given 
in  the  Engineering  News  of  June  7, 1906,  page  623.  (See  Pis.  XXIV, 
A;  XXV,  B.) 

2E TNA  (YOUNG,  OR  COMMISSARY)  BUILDING. 

The  steel-frame  structure  at  the  corner  of  Spear  and  Market 
streets,  locally  known  as  the  “commissary  building, 7;  because’ it  was 
said  to  have  been  erected  originally  with  a view  to  furnishing  offices 
for  the  Commissary  Department  of  the  Army,  rests  upon  piles, 
and  suffered  relatively  small  damage  from  the  earthquake.  PI. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


77 


XXV,  A , shows  the  corner  of  the  building  and  the  subsidence  of 
the  street  at  this  point.  The  inlet  at  the  corner  indicates  the  original 
level  of  the  street.  There  was  a vault  under  the  Market  street  side- 
walk, immediately  behind  the  wall  at  the  curb  line.  The  basement 
floor  in  this  vault  was  of  concrete  and  had  a total  thickness  of  7 or  8 
inches.  The  earthquake  caused  the  earth  to  bulge  up  in  the  portion 
of  the  basement  under  the  sidewalk,  rupturing  the  concrete  floor 
and  turning  it  up  on  its  edge,  so  that  where  there  had  previously 
been  a clear  headroom  of  7^  feet  the  highest  point  of  the  bulge  was 
within  3J  feet  of  the  beams  carrying  the  sidewalk.  The  columns 
were  of  steel,  protected  with  expanded  metal  and  plaster.  The 
girders  were  of  steel  and  the  space  between  them  was  spanned  by 
reenforced-concrete  construction.  The  reenforced-concrete  beams 
were  formed  on  the  lower  edge  by  a curved  piece  of  flat  steel  (PI. 
XXIX,  B).  The  concrete  floor  construction  was  damaged  by  the 
heat  to  such  an  extent  that  a heavy  load  of  sheet  iron  on  the  third 
floor  broke  through,  though  it  did  not  fall  through  bodily.  The 
expanded  metal  that  was  used  for  reenforcing  the  slabs  from  rib  to 
rib  evidently  got  hot  and  was  ruptured  at  this  point. 

The  cinder  concrete  used  in  the  floor  construction  of  this  building 
was  badly  damaged  by  the  heat,  although  the  heat  could  not  have 
been  very  intense,  as  otherwise  the  ribs,  with  their  exposed  metal 
reenforcement,  must  have  failed.  Moreover,  the  girders  did  not  have 
their  lower  flanges  protected,  yet  they  remained  straight.  A great 
many  of  the  ribs,  however,  were  deflected  very  considerably,  but, 
owing  to  the  fact  that  they  were  curved  to  begin  with,  this  deflection, 
due  to  the  fire  damage,  was  not  very  apparent.  The  columns  them- 
selves were  practically  uninjured,  although  the  column  covering  was 
severely  damaged  and  will  probably  have  to  be  totally  renewed. 
There  were  some  terra-cotta  partitions,  terra-cotta  furring,  and  furred 
ceilings  in  this  building,  all  of  which  totally  failed.  The  brick  wall 
at  the  west  side  of  the  building  exhibited  some  earthquake  cracks, 
and  at  a number  of  places  the  brickwork  spalled  under  the  heat. 

appraisers’  warehouse. 

The  appraisers’  warehouse  was  a very  heavy  structure,  built  on  the 
old-fashioned  monumental  plan.  (PI.  XXVIII,  A.)  It  was  entirely 
of  brickwork,  with  some  stone  trimmings,  and  the  exterior  brick- 
work was  laid  with  full  header  courses.  It  was  practically  undam- 
aged by  the  earthquake,  the  chimney  even  being  left  standing,  and  the 
fire  did  not  get  into  it.  It  is  probable  that  the  shock  at  the  site  of 
this  building  was  not  so  severe  as  it  was  at  some  other  places,  or  the 
chimneys,  at  any  rate,  would  have  been  thrown  down.  The  building 
itself  shows  a very  few  slight  cracks,  which  may  have  been  due  to 


78 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


ordinary  settling  and  not  at  all  to  earthquake.  Mr.  Roberts,  the  local 
representative  of  the  Supervising  Architect’s  Office,  informed  me  that 
during  the  construction  of  the  building  there  had  been  some  unequal 
settling,  so  that  one  end  was  about  1J  inches  lower  than  the  other, 
but  that  this  settling  had  been  at  a uniform  rate  from  one  end  to  the 
other,  so  that  it  had  caused  practically  no  damage.  On  the  interior 
there  were  many  solid  brick  partitions,  with  some  unprotected  cast- 
iron  columns.  The  floor  construction  was  of  steel  or  iron  beams 
and  segmental  brick  arches  with  a span  of  3 to  6 feet. 

It  is  worthy  of  note  that  immediately  after  the  earthquake  and 
fire  three  of  the  very  few  buildings  in  the  burned  district  which  wTere 
absolutely  open  and  ready  for  business  in  every  particular  were  the 
post-office,  the  mint,  and  the  appraisers’  warehouse.  The  massive 
construction  used  in  these  Government  buildings  would  appear  to 
have  been  a very  good  investment. 

ARONSON  BUILDING. 

The  ordinary  ten-story  steel-frame  structure  at  the  corner  of  Third 
and  Mission  streets  known  as  the  Aronson  Building  had  terra-cotta 
column  coverings  and  partitions  and  cinder-concrete  floors,  all  of 
which  were  of  the  types  described  in  this  paper  as  common  in  com- 
mercial buildings.  The  building  seems  to  have  been  occupied  for 
light  commercial  purposes,  and  the  fire  test  to  which  it  was  subjected 
was  therefore  somewhat  more  severe  than  that  prevailing  in  office 
buildings. 

A column  in  the  basement  was  buckled,  and  two  of  the  columns  on 
the  first  floor  were  badly  buckled  near  the  ceiling,  as  shown  in  PI. 
XXVII,  B.  These  results,  so  far  as  the  condition  of  the  fireproofing 
is  concerned,  are  typical  not  only  of  the  other  stories  of  the  Aronson 
Building,  but  of  similar  work  in  other  buildings  throughout  the 
burned  district.  Some  of  the  work  in  the  Aronson  Building  was  not 
severely  tested  by  the  fire  and  was  still  intact.  An  examination  of  it 
shows  that  it  was  as  well  done  as  similar  work  in  any  other  commer- 
cial building  in  San  Francisco.  Where  the  fire  was  not  very  hot  this  1 
kind  of  fireproofing  protected  the  steel  and  suffered  not  more  than  10 
or  15  per  cent  of  damage  itself;  where  the  fire  reached  the  average 
temperature  the  fireproofing  suffered  a loss  of  50  to  100  per  cent,  and 
where  the  fire  was  a little  hotter  than  the  average  the  total  loss  of  the 
fireproofing  and  serious  damage  to  the  steel  work  was  not  at  all 
uncommon.  Damage  to  fireproofing  such  as  that  here  described 
occurred  in  the  James  Flood  Building,  the  Emporium  Building,  the 
building  of  the  Spring  Valley  Water  Company,  the  Mills  Building,  I 
and  every  other  building  in  which  hollow  tiles  were  used. 

The  buckled  column  in  the  basement  was  about  the  worst  example 
of  this  sort  of  damage  that  I discovered,  although  I am  inclined  to  j 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


79 


think  that  in  one  or  two  other  buildings  in  which  there  was  a general 
collapse  of  the  steel  superstructure  worse  columns  than  this  one  could 
have  been  found  under  the  debris.  The  debris  was  not  cleared  away 
while  I was  in  San  Francisco,  so  I had  no  opportunity  to  see  the  con- 
dition of  many  columns  that  had  evidently  failed. 

The  basement  of  the  Aronson  Building  was  divided  into  several 
rooms  by  hollow-tile  partitions.  The  room  in  which  the  buckled 
column  was  located  had  evidently  contained  an  enormous  amount  of 
paper  in  some  form  or  other,  and  the  heat  generated  must  have  been 
very  intense.  The  fire  broke  through  the  hollow-tile  partition  which 
separated  this  room  from  the  adjacent  one,  but  there  was  very  little 
that  was  combustible  in  the  latter,  and  the  column  standing  there  had 
its  fireproof  covering  entirely  intact.  Examination  showed  that  the 
work  in  this  building  was  neither  better  nor  worse  than  the  average 
of  similar  work  anywhere  else  in  the  San  Francisco  commercial  build- 
ings. A plain  and  inevitable  inference  is  that  wherever  such  work 
was  practically  undamaged  the  fire  test  was  not  at  all  severe. 

In  the  same  part  of  the  basement  as  that  in  which  the  above- 
mentioned  column  was  situated — that  is,  under  the  Third  street  wall 
of  the  building — there  were  two  columns  covered  with  cinder  concrete. 
The  concrete  covering  on  one  column  made  a very  large  and  heavy 
pier;  on  the  other  it  was  about  4 inches  thick.  It  was  apparent 
that  the  heat  in  this  front  portion  of  the  room  was  not  quite  as 
severe  as  it  was  farther  back,  where  the  buckled  column  was.  Not 
only  was  there  very  much  less  evidence  of  fire  in  the  way  of  ashes, 
etc.,  but  the  general  indications  pointed  to  a considerably  lower  tem- 
perature— although  the  heat  at  this  point  was  very  severe,  neverthe- 
less. The  larger  cinder-concrete  pier  was  evidently  damaged  to 
some  extent  by  the  heat.  The  cement  had  apparently  been  dehy- 
drated to  a depth  of  one-fourth  to  three-eighths  of  an  inch  on  the 
flat  surface,  and  to  a greater  depth  at  the  corners.  The  other  pier 
showed  more  evidence  of  intense  heat.  It  stood  opposite  the  middle 
of  the  room,  where  there  seems  to  have  been  the  greatest  accumula- 
tion of  combustible  matter.  When  I first  saw  this  column  the  cinder 
concrete  was  dead  and  friable  to  a depth  of  nearly  an  inch.  How 
much  of  this  was  due  to  original  poor  quality  and  how  much  to  the 
action  of  the  fire  was  difficult  to  determine,  but  fire  damage  was 
very  evident.  This  pier  showed  on  the  surface  a number  of  longitu- 
dinal cracks  running  from  top  to  bottom,  indicating  that  there  had 
been  a tendency  for  the  concrete  to  fail  and  come  off  under  the  ex- 
pansion stresses.  At  a later  inspection  a part  of  the  concrete  covering 
of  this  column  had  been  knocked  off,  and  it  then  became  apparent  that 
the  cracks  above  referred  to  had  extended  entirely  in  to  the  surface  of 
the  column  itself,  and  enough  heat  had  got  in  to  partly  burn  off  the 
paint  along  the  inner  edges  of  the  cracks. 


80 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


The  stairways  in  this  building  had  apparently  been  partitioned 
off  by  hollow-tile  partitions,  but  these  were  totally  wrecked,  and  the 
stairways  were  in  such  condition  that  it  was  only  with  great  diffi- 
culty and  by  going  on  all  fours  that  they  could  be  used  to  reach  the 
upper  story.  In  the  west  wall  of  this  building  I saw  the  remains  of  a 
wire-glass  window,  with  metal  sash  and  frame,  which  had  been  prac- 
tically destroyed  by  the  heat — probably,  however,  as  a result  of  a 
simultaneous  attack  by  the  fire  from  both  sides.  Wire  glass  seems 
to  have  done  some  good  service  in  other  buildings  in  San  Francisco, 
although  in  the  Merchants’  Exchange,  as  in  the  Aronson  Building, 
it  failed  completely,  so  that  a constructing  engineer,  who  had  drawn 
his  conclusions  entirely  from  what  he  saw  in  the  Merchants’  Ex- 
change, was  disposed  to  condemn  wire  glass  outright. 

BULLOCK  & JONES  BUILDING. 

The  steel-frame  Bullock  & Jones  Building  was  faced  with  orna- 
mental terra  cotta,  with  hollow-tile  column  covering  and  reenforced- 
concrete  slabs  which  were  haunched  on  the  beams,  the  slab  reenforce- 
ment apparently  not  being  continuous  over  the  tops  of  the  beams. 
Some  of  the  floor  slabs  collapsed,  and  the  column  coverings  failed 
entirely.  Two  columns  in  the  third  story  had  buckled  in  the  same 
way  the  columns  buckled  in  the  Aronson  Building.  This  building 
was  rather  more  flimsy  even  than  the  average  commercial  building, 
and  the  fire  nearly  brought  it  down.  PL  XXVI,  A , is  an  interior 
view  showing  the  buckled  columns  in  the  second  story.  It  will  be 
observed  that  pipes  were  run  up  inside  of  the  column  coverings. 
Where  similar  conditions  existed  in  Baltimore  it  was  maintained  by 
those  interested  in  the  particular  system  of  column  covering  used 
that  the  pipes  had  got  hot,  expanded,  and  thrown  the  covering  off. 
My  own  opinion  was  and  is  that  the  covering  must  have  failed  first, 
otherwise  the  pipe  would  not  have  become  hot.  It  may  be  that  after 
the  covering  had  partially  failed,  the  pipe  got  hot  and  completed  the 
destruction,  but  if  the  covering  had  been  efficient  to  begin  with, 
there  would  have  been  no  trouble  with  the  pipe. 

A comparison  of  the  conditions  in  the  Bullock  & Jones  Building 
with  those  shown  in  other  views — for  example,  in  the  illustrations 
of  the  Aronson  Building — is  sufficient  to  justify  the  opinions  herein 
expressed.  PL  XXVI,  A,  shows  that  one  of  the  panels  of  the  floor 
system  had  collapsed.  My  examination  of  the  Bullock  & Jones 
Building  indicated  that  The  reenforced-concrete  floor  construction 
was  haunched  on  the  lower  flanges  of  the  floor  beams.  The  photo- 
graph confirms  this  observation,  as  will  be  seen  by  examining  the 
naked  floor  beam  which  appears  in  the  lower  left-hand  portion  of 
the  view.  The  reenforcement  of  a floor  slab  should  always  be  con- 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


81 


tinuous  over  the  top  of  the  beam ; otherwise  the  construction  is  noth- 
ing but  an  arch,  and  develops  the  thrust  to  be  expected  of  an  arch. 
Moreover,  as  a rule,  tie-rods  are  omitted  when  reenforced-concrete 
floor  slabs  are  used,  and  it  was  naturally  to  be  expected  that  reen- 
forced-concrete floor  slabs  of  this  type  would  collapse  to  some  extent ; 
the  wonder  is  that  they  did  not  collapse  to  a greater  extent  in  the 
Bullock  & Jones  Building.  The  fire  damage  to  ornamental  terra 
cotta  in  this  building  was  very  conspicuous. 

CALL  BUILDING. 

Of  all  the  commercial  buildings  in  San  Francisco,  by  far  the  most 
interesting  was  that  known  as  the  Call  (or  Spreckels)  Building,  at 
the  corner  of  Third  and  Market  streets.  This  building  is  remarkable 
for  the  care  and  skill  shown  in  the  design  of  its  steel  work.  It  is  a 
steel-frame  building,  all  the  walls,  floors,  partitions,  etc.,  being  car- 
ried on  steel  work.  It  has  15  main  stories,  in  addition  to  the  stories 
in  the  dome,  or  cupola,  and  rests  upon  a continuous  foundation  com- 
posed of  concrete  reenforced  with  steel  beams.  The  building  proper 
is  about  75  feet  square,  but  the  foundation  is  about  90  by  110  feet, 
and  was  carried  to  a depth  of  about  25  feet  below  the  sidewalk  level. 
A fairly  complete  and  satisfactory  description  of  this1  building  was 
published  in  the  Engineering  Record  of  April  9 and  16,  1898. 

In  the  first  four  stories  above  the  street  the  bents  of  the  steel  work 
adjacent  to  the  four  corners  of  the  building  on  each  side  were  braced 
with  solid  portal  braces.  In  addition,  eight  interior  bents  were 
braced  with  diagonal  tiebars  from  top  to  bottom.  At  all  junctions 
of  girders  and  beams  with  columns  knee  braces  were  used.  The  de- 
sign of  this  steel  work  is  well  worthy  of  study  by  anyone  interested  in 
such  structures.  It  is  probably,  on  the  whole,  the  best-designed 
piece  of  such  work  in  the  United  States.  Another  remarkable  thing 
about  it  is  that  the  execution  was  apparently  as  good  as  the  design. 
In  a number  of  places  where  the  fireproofing  had  come  off  the  connec- 
tions were  exposed,  and  the  workmanship  here  seemed  to  have  been 
practically  as  good  as  it  could  well  be  made.  I particularly  noticed 
the  column  bearings,  and  they  seemed  to  be  absolutely  close  and  true. 
Inaccurate  column  bearings  in  building  work  are  so  often  seen  that 
one  is  almost  justified  in  saying  that  they  are  the  rule  rather  than 
the  exception;  but  in  the  Call  Building  such  connections  as  were 
exposed  to  view  had  been  put  together  with  extreme  accuracy. 

The  column  covering  in  this  building  was  of  hollow  tiles,  about  3 
inches  thick,  with  very  thin  webs.  Partitions  were  built  of  the  same 
material.  The  floor  construction  was  of  reenforced  cinder  concrete. 
Some  furred  ceilings  composed  of  wire  lathing  and  light  furring 
strips  were  also  used.  The  outer  walls  were  furred  with  2-inch 


82 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


hollow  tiles.  When  I saw  the  building  the  column  coverings  and 
partitions  throughout  were  either  down  or  so  badly  shattered  that 
nearly  all  of  them  would  have  to  be  taken  down  and  rebuilt,  and 
the  furring  had  fallen  from  many  of  the  outer  walls.  The  chief 
engineer  of  the  building  stated  that  it  was  practically  undamaged 
immediately  after  the  earthquake,  and  that  the  fire  which  subse- 
quently gained  access  did  not  damage  it  very  much,  but  that  a large 
part  of  the  ruin  of  the  partitions  and  column  coverings  was  due  to 
the  concussions  from  the  dynamite  used  in  demolishing  dangerous 
walls  in  the  neighborhood. 

The  hollow-tile  covering  of  the  steel  work  came  down  pretty  gen- 
erally throughout  the  building.  Whether  or  not  this  failure  resulted 
from  the  fire,  close  examination  of  the  steel  work  proved  that  the 
tile  covering  was  totally  inadequate,  because  in  many  places  there 
had  been  heat  enough  to  burn  the  paint  entirely  off  the  steel  and  to 
leave  indications  of  high  temperature  on  the  metal  itself.  Photo- 
graphs taken  of  the  Call  Building  during  the  progress  of  the  fire 
indicate  that  the  fire  was  not  very  fierce,  yet,  in  my  judgment,  some 
of  the  steel  members  were  very  close  to  serious  damage  as  a result  of 
it.  So  magnificent  a piece  of  steel  work  deserved  better  fireproof 
covering  than  it  had;  but,  as  a matter  of  fact,  the  steel  itself  was 
observed  to  be  fire  blackened  in  many  places.  The  furred  ceilings  in 
this  building  in  general  suffered  so  much  damage  that  they  should 
be  taken  down  altogether.  The  marble  finish  throughout,  while  not 
absolutely  destroyed,  was  so  damaged  as  to  be  worthless.  The 
reenforced-concrete  floor  slabs  stood  fairly  well,  but  some  of  the 
concrete  looked  as  if  it  had  suffered  appreciably  from  the  heat. 

On  the  exterior  the  Call  Building  showed  absolutely  no  damage 
from  the  earthquake  except  in  the  story  immediately  above  the  main 
cornice,  where,  in  the  parts  adjacent  to  the  four  corners,  a few  stones 
had  evidently  slipped  so  that  the  joints  had  opened  up  for  possibly 
half  an  inch  or  more.  The  exterior  of  the  building  was  faced  with 
the  grayish-green  sandstone  which  is  used  for  so  many  buildings  in 
San  Francisco.  This  stone,  wherever  the  fire  struck  it,  not  only 
spalled  very  badly,  but  had  its  color  very  largely  burned  out,  so  that 
what  remained  was  a dull  and  lifeless  buff  gray,  the  green  having 
totally  disappeared. 

Examination  of  the  Call  Building  from  the  exterior  produced  the 
impression  that  it  was  slightly  out  of  plumb  to  the  southeast,  but 
later  information  showed  that  this  estimate  of  the  direction  in  which 
the  building  leaned  was  incorrect.  Captain  Kelly  kindly  sent  a man 
with  a plumb  line  to  verify  the  observation.  He  plumbed  the  build- 
ing from  the  tenth  floor,  as  its  dimensions  were  reduced  somewhat 
above  this  point.  He  found  that  the  building  leans  uniformly  toward 
Market  and  Third  streets;  at  the  tenth  floor  the  building  overhangs 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


88 


Market  street  by  8 inches  and  Third  street  by  10  inches.  This  indi- 
cates clearly  that  it  is  not  safe  to  trust  the  eye  in  the  matter  of  a 
building  out  of  plumb,  because  when  previously  examined — not  only 
once  but  several  times- — the  Call  Building  presented  the  appearance 
of  leaning  away  from  Market  street  instead  of  toward  it.  In  my 
judgment  the  deviation  from  the  vertical  in  this  building  may  have 
been  due  in  whole  or  in  part  to  the  earthquake,  but  it  is  not  at 
all  impossible  that  it  may  have  been  built  out  of  plumb.  With  the 
rigid  type  of  connections  used  in  the  Call  Building,  strict  mathe- 
matical accuracy  of  construction  at  all  points  would  be  essential  to 
insure  the  exact  perpendicularity  of  the  building.  As  this  accuracy 
is  practically  unattainable,  it  is  ordinarily  necessary  to  accept  slight 
deviations  from  the  plumb  line  and  probabty,  in  the  majority  of 
cases,  a certain  amount  of  torsion  in  the  frame  itself.  So  far  as 
these  deviations  are  kept  within  reasonable  limits  they  make  no 
serious  difference,  and  the  building  is  just  as  good  for  all  practical 
purposes  as  if  it  were  perfectly  plumb  and  true. 

On  the  whole,  the  foundations  and  steel  frame  of  this  building 
were  admirably  designed.  The  bracing  of  the  steel  work  seems  to 
have  taken  up  the  vibration  due  to  the  earthquake,  so  as  to  preserve 
the  masonry  of  the  outer  walls.  As  long  as  there  is  no  deflection 
sufficient  to  crack  the  masonry,  there  can  be  no  doubt  that  the  build- 
ing is  safe.  It  is  a question  whether  other  buildings  which  were  not 
so  well  braced,  and  in  which  the  piers  between  windows  were 
badly  shattered,  were  not  dangerously  near  collapse,  and  it  may  well 
be  doubted  whether  there  is  not  serious  damage  to  the  steel  work  as 
it  is.  This  matter  could  be  determined  only  by  uncovering  the  steel 
and  making  a detailed  inspection. 

The  only  safe  plan  in  the  construction  of  steel- frame  buildings 
is  the  one  followed  in  the  Call  Building — that  is,  to  brace  the  steel 
work  so  that  by  itself  it  is  able  to  resist  the  stresses  due  to  the  vibra- 
tion. The  engineer  who  designed  the  foundations  and  steel  frame 
of  this  building  may  well  be  gratified  at  the  admirable  manner  in 
which  his  structure  fulfilled  its  purpose.  Had  the  building  been  as 
well  designed  to  resist  fire  as  to  resist  earthquake,  it  is  probable  that 
the  total  damage  would  have  been  very  much  less  than  it  was. 

CHRONICLE  BUILDINGS  (OLD  AND  NEW) . 

The  old  Chronicle  Building  (PI.  XXX,  B)  seems  to  have  been 
built  in  two  parts — a west  and  an  east  wing.  The  west  wing  had 
protected  cast-iron  columns,  rolled  beams,  and  terra-cotta  fireproof- 
ing. The  interior  structure  had  entirely  collapsed,  apparently  from 
the  heat.  It  was  impossible,  with  the  debris  piled  around  it,  to 
determine  just  what  the  cause  of  the  failure  was,  but  it  was  probably 


84 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


due  to  the  buckling  or  rupture  of  a lower-story  column  by  the  fire. 
In  the  east  wing  of  the  old  building  the  terra-cotta  fireproofing  had 
suffered,  to  a considerable  extent,  the  typical  damage  which  is  de- 
scribed in  connection  with  the  Aronson  Building  (p.  78)  and  in  the 
general  discussion  of  the  subject  (p.  72).  Many  floor  tiles  had  lost 
their  lower  webs. 

The  new  Chronicle  Building  (also  shown  iii  PI.  XXX,  B)  was 
badly  racked  by  the  earthquake  from  the  point  where  it  rose  above 
the  neighboring  buildings  to  the  top.  It  seems  to  have  been  pro- 
vided with  knee  braces  tending  to  stiffen  it  in  a direction  parallel 
to  the  Kearney  street  front.  In  the  first  story,  at  any  rate,  there 
were  some  diagonal  braces  in  the  steel  work  of  the  north  wall.  The 
worst  damage  was  to  the  masonry  of  the  Kearney  street  front;  the 
shattering  of  this  masonry  can  be  observed  by  a close  inspection  of 
PI.  XXX,  B.  This  building  was  unfinished.  It  had  hollow-tile 
fireproofing,  including  partitions.  The  burning  out  of  the  window 
trim  and  of  whatever  combustible  matter  may  haA^e  been  in  the 
building,  caused  a good  deal  of  damage  to  the  hollow-tile  floors, 
especially  near  the  windows,  where  the  lower  webs  came  off  almost 
completely. 

The  old  Chronicle  Building  seems  to  have  suffered  very  little 
from  the  earthquake,  notwithstanding  it  must  have  acted  as  a buttress 
for  the  new  building. 

CITY  HALL  AND  HALL  OF  RECORDS. 

The  new  city  hall  in  San  Francisco  (PI.  XXXI),  together  with 
the  hall  of  records,  which  adjoins  it  and  which  formed  practically 
a part  of  one  and  the  same  structure,  was  a massive  brick  building 
with  steel  floor  beams.  This  building  had  corrugated-iron  floor 
arches,  leveled  up  with  concrete.  There  were  some  naked  cast-iron 
columns  where  the  span  from  wall  to  wall  was  too  great  for  the 
beams.  All  interior  partitions  of  any  importance  were  of  brick  and 
rather  heavy.  In  the  basement  and  subbasement  the  corrugated-iron 
arches  were  left  exposed.  Everywhere  else  there  was  a ceiling  car- 
ried on  a form  of  metal  lathing  consisting  of  sheets  of  metal  crimped 
so  as  to  form  dovetailed  grooves  or  ribs;  the  plaster,  being  pressed 
up  against  this  lathing  and  into  the  dovetailed  grooves,  was  enabled 
to  hold  on  by  the  key  thus  formed.  The  girders  in  the  building  were 
protected  by  a wrapping  of  this  metal  lathing  finished  on  the  exterior 
with  plaster.  The  brickwork  in  the  city  hall  was  made  of  a very 
good  quality  of  common  bricks.  The  mortar  appeared  to  be  lime 
mortar  gaged  with  cement,  and  was  distinctly  superior  to  lime  mortar 
pure  and  simple.  The  workmanship  was  also  above  the  average. 
The  bricks  were  not  as  well  laid  as  they  might  be,  yet  it  was  not  poor 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


85 


work  by  any  means.  I found  a few  places  where  joints  were  not 
well  filled,  but  not  a greater  number  of  such  places  than  one  would 
expect  to  find  even  in  fairly  good  work.  On  the  exterior  the  build- 
ing was  finished  with  stucco,  which  was  tinted  to  imitate  the  grayish- 
green  sandstone  so  much  used  for  building  purposes  in  San  Francisco. 

The  city  hall  was  of  an  irregular  plan,  as  it  was  built  on  a trian- 
gular lot.  The  building  contained  in  the  western  part  an  interior 
court,  in  which  a nonfireproof  structure  had  been  erected  prior  to  the 
earthquake  and  fire  to  accommodate  the  fire-alarm  headquarters. 
On  the  southeast  front  of  the  building  a little  to  the  east  of  the 
center  was  a rotunda  with  a tower  and  dome  above  it.  This  tower 
was  built  of  brickwork  up  to  the  base  of  the  upper  of  two  peristyles 
of  free  pillars  around  the  outside  of  the  tower.  This  peristyle  was 
composed  of  steel  columns  covered  with  hollow  tiles,  so  ks  to  form  a 
pillar  of  circular  section  with  an  entasis.  The  walls  of  the  tower 
from  the  base  of  this  peristyle  up  also  seem  to  have  been  of  hollow 
tiles.  At  the  base  of  the  dome  was  a floor  composed  of  terra-cotta 
flat  arches.  It  was  reported  that  the  masonry  of  the  building  had 
been  reenforced  to  a great  extent  with  embedded  steel  bars  for  the 
purpose  of  increasing  its  resistance  to  earthquake.  I did  not  notice 
any  such  bars  myself,  but  it  was  very  difficult  to  get  Such  access  to 
the  debris  as  would  have  permitted  the  verification  of  this  point. 

In  a general  way  it  may  be  said  that  the  southwest  half  of  the 
building  was  practically  destroyed  by  the  earthquake.  The  heavy 
masonry  was  thrown  down,  so  that  the  entire  southwest  half  of  the 
lower  was  left  entirely  exposed,  the  dome  standing  on  the  steel  work 
alone.  The  remaining  half  of  the  building  showed  considerable 
damage  from  the  earthquake,  but  the  principal  damage  here  was  due 
to  the  fire.  PI.  XXXI  gives  a fair  idea  of  the  earthquake  damage 
in  the  southwest  half  of  the  building. 

It  will  be  observed  that  some  of  the  projecting  pilasters  on  the 
exterior  of  the  wall  were  badly  cracked.  A singular  action  of  the 
earthquake,  as  exhibited  here  and  in  other  places,  was  the  tendency 
to  shear  off  projecting  pilasters  even  though  they  were  built  of  the 
same  material  as  the  wall  and  well  bonded  to  it.  In  my  judgment 
this  action  was  due  to  the  fact  that  the  earthquake  caused  the  wall 
to  rock  slightly  sidewise.  When  it  rocked  toward  the  side  from 
which  the  pilasters  projected,  the  entire  weight  would  be  for  an 
instant  concentrated  on  the  base  of  the  pilaster  in  such  a way  as  to 
tend  to  shear  it  loose  from  the  wall,  which  actually  happened  in 
many  cases,  the  wall  presenting  no  other  evidence  of  damage  what- 
soever. Instances  of  this  damage  are  pointed  out  in  the  discussion 
of  other  buildings. 

Examination  of  PI.  XXXI,  especially  with  a reading  glass,  will 
show  that  many  of  the  diagonal  braces  in  the  steel  work  of  the  tower 
7171— Bull.  324—07 7 


86  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

were  stretched  beyond  their  elastic  limit.  I found,  on  personal  exam- 
ination in  the  field,  that  many  of  the  wind  struts  had  almost  slipped, 
from  their  seats  on  the  columns.  The  bolt  holes  or  rivet  holes  in- 
tended for  bolts  or  rivets  to  hold  the  struts  in  place  between  their 
seats  were  not  filled.  Whether  this  was  due  to  the  fact  that  they  had 
been  sheared  by  the  earthquake  or  whether  they  had  been  omitted  in 
erection,  I could  not  determine  definitely.  The  latter  will  seem  a 
plausible  supposition  to  anyone  familiar  with  the  way  in  which  the 
average  erecting  gang  does  its  work.  A few  of  the  wind  struts  had 
absolutely  slipped  from  their  seats  and  fallen  down;  but  it  was  not 
possible  to  determine  from  the  visible  evidence  whether  this  damage 
was  due  to  the  earthquake  or  to  the  precipitation  of  the  mass  of 
masonry  upon  the  struts  as  a result  of  the  failure  of  the  outer  walls. 
Examination  of  the  diagonal  tie-rods  made  it  apparent  that  some 
of  them  may  have  been  stretched  and  bent  by  the  mass  of  masonry 
falling  upon  them,  but  that  others  had  very  clearly  been  stretched 
beyond  the  elastic  limit  by  the  vibration  of  the  tower  during  the 
earthquake.  In  inspecting  the  inside  of  the  rotunda  I observed  con- 
siderable earthquake  damage  to  the  tower,  including  the  stretching 
of  a pair  of  diagonal  tie-rods  in  the  dome  by  the  impact  of  the 
falling  material.  The  terra-cotta  floor  at  the  base  of  the  dome  was 
absolutely  intact,  so  far  as  could  be  determined.  I made  an  effort 
to  get  out  upon  the  steel  work  of  the  tower  to  climb  it,  but  could 
only  get  as  high  as  the  gallery  in  the  rotunda  on  a level  with  the 
upper  floor  of  the  main  building.  The  means  of  access  to  the  higher 
points  had  been  evidently  destroyed  by  the  earthquake.  The  portion 
of  the  tower  above  this  point,  however,  was  carefully  examined 
through  a very  good  field  glass,  which  enabled  me  to  see  a great  many 
details  practically  as  well  as  if  I had  been  able  to  climb  the  tower 
itself.  Among  other  things,  it  indicated  very  clearly  that  this  terra- 
cotta floor  was  of  a much  better  type  than  those  ordinarily  put  into 
commercial  buildings. 

Around  a portion  of  the  rotunda  there  was  an  inner  wall,  built  of 
hollow  tiles,  which  the  earthquake  had  so  shattered  that  practically 
the  entire  wall  would  have  to  be  taken  down  in  order  to  make  ade- 
quate repair.  It  will  be  noted  by  an  examination  of  PI.  XXXI  that 
the  brickwork  of  the  building  fell  and  broke  up  into  large  masses. 
If  it  had  been  very  poor  brickwork  it  would  have  broken  up,  for  the 
most  part,  into  individual  bricks,  and  the  fact  that  it  did  not  do  so 
is  proof  that  it  was  not  of  a kind  to  call  for  serious  censure  of  the 
architect  or  contractor.  There  was  practically  no  fire  in  the  rotunda 
of  the  tower  of  the. city  hall.  Opposite  the  main  corridor  connecting 
with  the  portion  of  the  building  to  the  north  the  varnish  on  the 
hand  rail  in  the  upper  galleries  was  scorched,  but  on  the  main  floor 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES.  87 

a temporary  platform  covered  with  bunting,  which  had  evidently 
been  used  on  the  occasion  of  some  meeting,  was  practically  undam- 
aged, except  for  the  material  which  had  been  precipitated  upon  it. 

The  main  structure  of  the  building  itself,  to  the  southwest  of  the 
tower,  as  shown  in  the  foreground  and  to  the  left  in  Pl.  XXXI,  was 
badly  racked  by  the  earthquake.  There  was  very  little  damage  from 
fire  in  this  part  of  the  building.  Either  the  vibration  due  to  the 
earthquake  or  the  impact  of  falling  material  removed  a good  deal 
of  plaster  from  the  walls  in  the  part  of  the  building  immediately 
behind  the  two  columns  that  are  still  standing,  with  the  portion  of 
the  entablature  that  they  supported.  A large  part  of  the  building 
was  entirely  gutted  by  the  fire,  so  that,  in  my  judgment,  it  would  cost 
about  as  much  to  remove  the  debris  and  restore  this  building  as  it 
cost  to  put  up  the  building  originally. 

In  the  northwest  corner  of  the  building  there  was  a pavilion  which 
had  a row  of  free  columns  still  standing.  In  the  middle  of  the  west 
front  of  the  building  there  had  been  a pavilion  with  a similar  row 
of  columns,  all  of  which,  with  their  entablatures,  were  precipitated 
into  the  street.  These  columns  were  composed  of  drums  of  cast  iron 
with  annular  rebates  which  enabled  them  to  be  securely  seated  and 
centered  on  each  other.  The  interior  of  each  shaft  was  filled  with 
broken-brick  concrete  of  a very  good  quality.  The  columns  were 
very  heavy  and  massive,  and  it  must  have  required  an  extremely 
severe  shock  to  detach  their  entablatures  from  the  rest  of  the  build- 
ing and  then  to  throw  the  whole  mass  into  the  street. 

The  effect  of  the  fire  on  the  interior  of  the  city  hall  was  very  inter- 
esting. Some  parts  of  the  ceiling  remained  in  place  sufficiently  long 
to  protect  the  corrugated-iron  arches  from  damage;  in  fact,  some  of 
the  ceiling  did  not  come  down  at  all.  Such  a case  is  presented  in  PI. 
XXVI,  i?,  which  shows  the  incipient  failure  of  a naked  cast-iron 
column  and  a ceiling  that  was  evidently  on  the  point  of  coming  down. 
Where  the  fire  was  intense  it  brought  the  ceiling  down  in  time 
to  permit  serious  damage  to  the  corrugated-iron  arches  and  their  con- 
crete filling.  Wherever  these  arches  were  exposed  directly  to  much 
heat  the  first  effect  was  to  cause  them  to  expand  and  rise  at  the 
crown,  which  generally  resulted  in  shattering  the  concrete  filling  im- 
mediately over  the  crown.  Further  application  of  the  heat  caused 
the  corrugated-iron  arch  to  soften  and  come  down  altogether.  When 
it  did,  the  concrete  followed  it,  the  portion  at  the  crown  being  too 
much  shattered  to  act  as  a key.  In  this  way  the  total  collapse  of 
large  areas  of  floor  construction  in  the  city  hall  was  brought  about. 
The  concrete  arch  would  have  stood  better  alone  than  it  did  with  cor- 
rugated iron  underneath  it;  indeed,  it  is  doubtful  whether  any  of  the 
concrete  arches  would  have  collapsed  but  for  the  damage  done  by  the 
expansion  of  the  corrugated  iron.  The  concrete  was  of  a very  fair 


88 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


quality  and  the  arches  were  very  heavy.  Many  of  the  floor  beams 
were  24  inches  deep,  and  that  was  consequently  the  depth  of  concrete 
at  the  haunches.  The  thickness  at  the  crown  seems  to  have  been  not 
less  than  5 or  6 inches,  and  the  span  between  floor  beams  was  not 
more  than  6 or  7 feet.  A concrete  arch  of  such  dimensions  and  such 
span,  even  though  it  had  been  made  of  very  poor  concrete,  should 
have  stood  perfectly  well  had  it  been  depending  on  its  own  power  of 
resistance  alone.  In  a number  of  places  where  the  floor  did  not  col- 
lapse the  effect  of  heat  on  the  exposed  lower  flanges  of  the  24-inch 
beams  was  sufficient  to  produce  a deflection  of  6 or  7 inches  on  a span 
of  25  or  30  feet.  This  result  indicates  clearly  the  necessity  of  pro- 
tecting the  exposed  flanges  of  all  beams. 

PI.  XXVI,  Z?,  shows  some  unconsumed  papers  about  the  base 
of  the  cast-iron  column.  These  papers  came  from  a vault  which 
opened  into  this  room  and  the  contents  of  which  were  charred, 
but  not  destroyed  ; all  the  combustible  contents  of  the  room  proper 
were  destroyed.  The  dark  splotches  on  the  wall  in  the  background 
are  due  to  spalling  of  the  brickwork  at  the  surface  under  the  influ- 
ence of  the  fire.  This  phenomenon  was  noticed  in  a number  of  places 
in  San  Francisco,  just  as  it  was  in  Baltimore;  but  as  a rule  the  spall- 
ing did  not  penetrate  to  a greater  depth  than  half  an  inch,  and  the 
wall  itself  was  practically  as  good  as  before.  In  the  fire  at  San  Fran- 
cisco, as  in  every  oilier  large  fire,  the  right  kind  of  brickwork  proved 
to  be  more  resistant  than  any  other  material. 

A good  deal  of  the  plaster  on  the  interior  walls  in  the  city  hall 
was  on  wooden  furring  studs  and  wooden  laths.  Why  this  kind  of 
work  should  have  been  done  is  beyond  comprehension.  Many  of  the 
corridors  would  have  suffered  practically  no  damage  but  for  this  one 
circumstance.  As  the  fire  burned  out  the  wooden  trim  of  openings 
between  the  corridors  and  the  rooms  it  gained  access  to  the  wooden 
furring  and  burned  it  out  behind  the  plaster,  thereby  bringing  most 
of  the  plaster  down.  There  were,  however,  many  square  yards  still 
standing,  although  the  wooden  furring  studs  and  laths  had  been 
burned  out  behind.  There  would  appear  to  have  been  no  reason  for 
furring  these  interior  walls;  the  plaster  could  just  as  well  have  been 
applied  to  the  brickwork  itself.  As  a matter  of  fact,  in  many  parts 
of  the  building  it  was  so  applied,  though  in  other  parts  the  walls 
were  furred  with  metal  lathing  and  studs.  Why  a uniform  treat- 
ment was  not  adopted  is  not  apparent. 

The  halls  of  the  building  were  generally  floored  with  marble  tile. 
Even  where  the  heat  had  apparently  not  been  very  intense  these  tile 
floors  expanded  and  came  up,  and  the  marble  was  rendered  chalky, 
while  the  color  was  completely  ruined. 

In  this  building  a number  of  girders  or  lintels  rested  upon  stone 
templates,  which  were  exposed  at  the  face  of  the  wall.  All  such 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


89 


templates  that  were  subjected  to  the  heat  were  badly  spalled  and  shat- 
tered, and  one  or  two  of  them  had  failed  sufficiently  to  permit  the 
ends  of  the  girders  to  settle  an  inch  or  more.  I also  noticed  a num- 
ber of  places  in  the  walls  of  the  building  where  the  fire  had  evidently 
found  its  way  into  the  interior  of  unfilled  joints  through  very  small 
and  tortuous  passages.  \ 

The  hall  of  records  was  connected  with  the  city  hall  by  means  of 
an  arcaded  corridor.  The  building  was  circular  and  all  the  floors 
above  the  first  were  pierced  so  that  they  practically  formed  galleries. 
The  beams  supporting  these  upper  floors  or  galleries  were  of  steel, 
set  radially  and  supported  at  their  inner  ends  by  girders  carried  on 
a peristyle  of  12  circular  cast-iron  columns,  which  had  no  fireproof 
covering  of  any  sort.  The  floor  arches  were  segmental  arches  of 
common  bricks.  The  lower  flanges  of  the  beams  were  exposed,  but 
the  evidence  indicated  that  there  must  have  been  a suspended  ceiling 
of  some  sort  below  the  fireproof  floor  construction,  although  it  was 
impossible  to  determine  its  nature.  It  is  probable  that  it  was  carried 
on  combustible  supports  of  some  kind,  which  have  totally  disap- 
peared. As  the  records  had  been  carried  away  from  this  building 
before  the  fire  reached  it  the  heat  within  it  was  not  very  intense  and 
the  interior  of  the  structure  was  standing  in  a comparatively  undam- 
aged condition,  except  for  finish.  The  exterior  walls,  however,  were 
badly  shattered  by  the  earthquake.  The  window  shutters  were  of 
iron,  and  if  they  had  remained  in  place,  considering  the  situation  of 
this  building,  would  probably  have  kept  the  fire  out.  As  indicated 
in  the  view,  however,  the  earthquake  wrenched  some  of  these  shutters, 
with  their  surrounding  masonry,  entirely  out  of  the  wall,  thereby, 
of  course,  leaving  easy  access  for  the  flames. 

As  previously  stated,  it  is  my  opinion  that  to  remove  the  debris 
and  restore  the  city  hall,  including  the  hall  of  records,  to  its  original 
condition  would  cost  as  much  as  the  entire  building  cost  in  the  begin- 
ning. As  it  was  so  badly  damaged  by  the  shock  it  would  apparently 
be  wise  to  remove  it  altogether  and  build  a structure  of  another  type 
designed  to  resist  earthquakes. 

COWELL  BUILDING. 

No  special  interest  attaches  to  the  Cowell  Building,  except  that  it 
seems  to  have  been  more  flimsy  than  the  average.  It  had  unprotected 
steel  work  and  girders  and  wooden- joisted  floors.  The  effect  of  fire 
on  the  unprotected  steel  work  is  well  illustrated  in  PL  LI,  B. 

CROCKER  BUILDING. 

The  Crocker  Building  had  a steel  frame  and  hollow-tile  fireproof- 
ing. Some  of  the  tile  arches  had  totally  collapsed,  and  over  large 


90 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


areas — probably  at  least  30  per  cent  of  the  whole — they  had  lost  their 
lower  webs.  There  was  nothing  of  special  interest  in  this  building 
more  than  has  been  described  with  other  buildings.  The  damage 
seemed  to  be  about  as  great  as  the  average — probably  more  than  60 
per  cent. 

CROCKER  ESTATE  BUILDING. 

PL  XXVIII,  B , shows  the  kind  of  damage  to  ornamental  terra 
cotta  which  is  typical  of  both  earthquake  and  fire  action.  This  par- 
ticular view  was  selected  because  it  was  possible  to  take  it  from  a 
point  near  by  so  as  to  show  the  damage  in  detail.  The  Crocker 
Estate  Building,  a part  of  which  is  shown  in  the  view,  had  cinder- 
concrete  floor  slabs,  rolled  beams  and  girders,  and  naked  cast-iron 
columns.  The  fire  was  evidently  not  very  hot  in  this  building.  The 
lower  flanges  of  the  beams  and  girders  were  covered  with  expanded 
metal  and  plaster.  The  webs  of  the  beams  were  protected  with  cinder 
concrete  built  out  solid  from  the  webs  to  the  edge  of  the  flange.  The 
rear  portion  of  this  building  and  a building  of  similar  construction 
on  the  east  had  largely  collapsed,  apparently  as  a result  of  the  action 
of  the  fire  on  the  naked  cast-iron  columns.  At  this  and  every  other 
point  where  exposed  cast-iron  columns  had  failed  it  was  often  noticed 
that  the  heads  of  the  columns  broke  off  and  remained  attached  to 
girders  and  beams  by  means  of  the  lugs  and  bolts.  This  result  con- 
firms conclusions  derived  from  certain  experiments  made  a number 
of  years  ago,  to  the  effect  that  the  lugs,  ribs,  etc.,  at  the  heads  of  cast- 
iron  columns  are  the  source  of  severe  shrinkage  stresses,  with  conse- 
quent weakness  in  the  column. 

DEWEY  MONUMENT. 

The  Dewey  monument,  in  Union  Square,  is  shown  in  PL  XXX,  A. 
Careful  examination  indicates  that  the  upper  stone  of  the  shaft  has 
slipped  to  the  left  by  an  appreciable  amount — apparently  about  an 
inch.  The  second  stone  has  slipped  about  three-fourths  as  far,  and 
the  third  stone  from  the  top  about  one-fourth  of  an  inch.  I was 
informed  that  there  is  a steel  bar  running  up  through  the  center  of 
the  shaft.  This  construction,  if  it  was  used,  explains  why  the  monu- 
ment was  not  thrown  to  the  ground,  as  it  otherwise  must  have  been. 

EMPORIUM. 

The  Emporium  was  a large  department  store  on  the  south  side  of 
Market  street,  between  Fourth  and  Fifth  streets  (Pl.  XXXII).  The 
only  portion  of  its  interior  structure  which  remained  had  been  carried 
by  a steel  frame.  It  is  reported,  however,  that  mill  construction  had 
been  used  for  the  upper  stories  in  a portion  of  the  building.  It  is  also 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


91 


reported  that  this  building  was  dynamited  three  times  during  the 
progress  of  the  fire,  although  I was  assured  by  a policeman,  who 
claimed  to  have  been  on  duty  during  the  whole  time,  that  this  report 
was  not  true.  Under  the  circumstances,  it  is  a little  difficult  to  draw 
a reliable  conclusion  from  the  state  of  affairs  in  the  Emporium. 
However,  examination  (if  the  ruins  indicated  very  strongly  that  much 
of  the  trouble  was  due  to  the  inadequacy  of  the  fireproof  protection 
to  the  steel  work. 

PI.  XXXII,  A,  is  a general  view  of  the  collapsed  portion  of  the 
building  and  illustrates  the  failure  of  the  terra-cotta  column  covering 
in  various  stages.  The  hollow-tile  end-construction  arches  in  the 
mezzanine  floor  had  collapsed  over  considerable  areas,  under  the 
influence  of  heat  alone,  as  the  evidence  plainly  indicated  that  nothing 
could  have  been  precipitated  upon  them  and  that  they  were  not  sub- 
jected to  an  explosion.  A considerable  portion  of  the  rear  wall  of 
the  Emporium,  which  had  been  thrown  down,  probably  partly  by 
earthquake  and  partly  by  the  fire,  presented  one  case  of  very  excellent 
mortar  used  in  a commercial  building.  The  mortar  was  better  than 
the  bricks,  and  both  were  of  good  quality.  The  fireproofing  in  the 
lower  part  of  the  building  was  quite  as  good  as  that  ordinarily  found 
in  similar  structures  throughout  the  country.  In  fact,  it  would  be 
easy  to  point  out  department  stores  not  so  well  fireproofed  as  the 
lower  part  of  the  Emporium. 

I have  always  been  of  the  opinion  that  the  Horne  store  in  Pitts- 
burg, which  was  the  first  large  fireproof  department  store  to  be 
tested  by  fire,  was  really  closer  to  collapse  from  the  heat  than  is 
generally  believed.  After  the  covering  has  been  stripped  from  a 
steel  column,  the  time  and  heat  required  to  bring  it  down  are  not 
very  great.  The  fact  that  the  covering  comes  off  during  a fire  is 
absolute  proof  that  it  is  wholly  inadequate.  If  the  steel  column 
stands  up,  notwithstanding  the  loss  of  its  covering,  it  is  due  to 
good  luck  and  not  at  all  to  good  fireproofing.  In  the  Horne  store 
the  covering  was  stripped  from  a number  of  columns ; in  the  Empo- 
rium Building  the  same  thing  happened,  but  the  heat  continued  a 
little  longer,  and  there  is  no  doubt  in  my  mind,  after  an  examination 
of  the  ruins,  that  at  least  a portion  of  the  collapse  was  due  to  the 
failure  of  the  columns  under  heat.  The  floor  tiles  in  the  Emporium 
Building  lost  their  lower  webs  in  large  quantities,  where  the  arches 
themselves  did  not  collapse;  and  tiles  in  the  column  covering  which 
did  not  come  off  bodily  also  lost  their  exposed  webs  in  considerable 
quantities.  The  ruins  of  the  Emporium  were  in  a very  dangerous 
condition,  so  that  a detailed  inspection  was  not  practicable;  and  it 
is  doubtful  whether  any  useful  results  would  have  followed,  because 
the  fireproofing  was  of  the  ordinary  commercial  type  which  has 
often  enough  been  proved  inadequate  to  resist  a serious  fire. 


92  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

FAIRMOUNT  HOTEL. 

The  lower  two  stories  of  the  Fairmount  Hotel  (PI.  XXXIV)  were 
of  concrete.  The  next  story,  the  first,  was  built  of  granite,  appar- 
ently backed  with  brickwork,  and  above  that  the  building  was  faced 
with  ornamental  terra  cotta.  The  earthquake  damage  to  this  terra 
cotta  was  severe.  Neither  the  granite  nor  the  concrete  walls  of  this 
building  seemed  to  have  suffered  materially  from  the  earthquake, 
but  the  granite  was  badly  damaged  by  the  fire.  The  building  was 
surrounded  by  a wide  open  space,  and  the  fire  must  have  been  very 
fierce  in  its  vicinity  to  have  ignited  it.  I was  informed  that  consid- 
erable damage  was  done  to  the  steel  work  and  fireproofing  in  this 
building;  but  as  the  owners,  or  at  least  those  in  charge,  objected  to 
having  it  inspected,  and  as  it  was  an  unfinished  building,  I made  no 
examination  of  its  interior.  If,  under  the  circumstances,  it  suf- 
fered seriously  from  the  fire,  the  only  conclusion  that  could  have 
been  drawn  was  that  the  fireproofing  was  very  poorly  done. 

» 

JAMES  FLOOD  BUILDING. 

The  new  James  Flood  office  building,  situated  on  the  north  side  of 
Market  street,  opposite  the  Emporium  Building,  had  a steel  frame, 
segmental  hollow-tile  floor  arches,  terra-cotta  column  covering  and 
partitions,  and  furred  ceilings  of  metal  lath  and  plaster.  The  hol- 
low-tile column  covering  and  partitions  failed  in  this  building  in 
the  same  manner  as  in  others,  and  to  about  the  same  extent  as  in  the 
average  building.  The  lower  stories  seem  to  have  been  occupied  for 
mercantile  purposes,  and  here  the  fire  damage  was  greater  than  it 
was  above.  PI.  XXXV,  A,  is  a view  taken  in  the  first  story  of  the 
Market  street  wing.  The  second  and  third  columns  from  the  front 
are  slightly  buckled  to  the  right.  They  were  covered  with  hollow 
tiles  in  about  the  same  way  as  the  columns  shown  in  the  Aronson 
Building.  The  columns  in  the  James  Flood  Building  were  Z-bar 
columns  and  were  filled  in  solidly  with  brickwork,  in  addition  to  the 
hollow-tile  covering  shown  in  the  view.  In  my  judgment,  this 
construction  was  the  only  thing  that  saved  the  Market  street  wing 
of  this  building  from  collapse,  because  there  was  every  evidence  that 
the  columns  which  were  found  slightly  buckled  had  reached  a dan- 
gerous temperature,  and  would  probably  have  come  down  and 
wrecked  all  of  the  building  above  them  had  it  not  been  for  the  stiffen- 
ing effect  of  the  brick  filling. 

PI.  XXXIII,  B , shows  a doorway  in  the  west  front  of  the  James 
Flood  Building  illustrating  the  damage  by  earthquake  to  the  sand- 
stone piers.  The  stone  used  in  this  building  was  the  same  grayish- 
green  sandstone  that  is  described  in  connection  with  other  buildings, 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


93 


and  at  each  principal  entrance  there  was  a groined-arch  ceiling  made 
of  it.  These  ceilings  were  so  badly  cracked  and  damaged  that  they 
will  probably  have  to  be  taken  down  and  rebuilt. 

GRANT  BUILDING. 

The  structure  at  Seventh  and  Market  streets  known  as  the  Grant 
Building  illustrated  the  capricious  variation  in  intensity  of  the  earth- 
quake shock  within  short  distances.  This  building  was  separated 
from  the  post-office  by  a very  narrow  street,  hardly  wider  than  an 
alley.  The  building  had  cinder-concrete  floor  slabs,  furred  ceilings 
in  the  upper  stories,  and  terra-cotta  partitions.  Although  it  was  a 
commercial  building  of  very  ordinary  type,  it  was  only  slightly 
damaged  by  the  earthquake,  but  was  gutted  by  fire.  It  was  entirely 
outside  the  area  of  surface  disturbance,  the  streets  in  its  vicinity 
showing  no  signs  of  settlement  or  upheaval.  The  fire  was  not  very 
hot  apparently,  but  was  just  about  able  to  take  the  plaster  off  the 
under  part  of  the  floor  construction  without  seriously  damaging  the 
latter.  The  terra-cotta  partitions  were  all  down.  There  was  no 
evidence  of  superiority  of  construction,  hoAvever,  as  everything 
pointed  to  moderate  tests  by  both  earthquake  and  fire. 

HALL  OF  JUSTICE. 

The  Hall  of  Justice  was  one  of  the  municipal  buildings  which  was 
seriously  damaged  by  the  earthquake.  A general  view  is  shown  in 
PI.  XXXIX,  A,  but  does  not  bring  out  the  damage  that  really 
occurred.  In  the  basement  of  this  building  was  another  example  of 
buckled  columns.  The  columns  were  covered  with  expanded  metal 
and  plaster.  This  covering  failed  at  a point  near  the  floor,  and  the 
columns  buckled  and  sank,  producing  the  same  effect  as  if  they  had 
been  punched  into  the  ground.  The  column  coverings  throughout 
this  building  failed  very  generally  from  the  fire. 

KAMM  BUILDING. 

The  Kamm  Building  was  situated  on  Market  street,  west  of  the 
Call  Building.  The  rear  portion  was  extended  eastward  by  a short 
ell,  so  that  it  was  wider  than  the  front.  It  was  occupied  in  the 
first  story  and  basement  by  a wall-paper  establishment.  The  columns 
were  protected  by  metal  lathing  and  plaster. 

The  burning  of  the  wall  paper  in  the  basement  caused  general 
buckling  of  the  basement  columns  to  such  an  extent  as  to  result  in 
the  collapse  of  all  the  interior  framework  of  practically  the  entire 
rear  portion  of  the  building.  A good  view  of  this  building  is  to 
be  found  in  the  Engineering  Record  of  May  26,  1906,  on  page  645. 


94 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


KOHL  BUILDING. 

The  Kohl  Building  was  of  steel-frame  construction  faced  with  the 
grayish-green  sandstone  which  is  referred  to  so  often.  It  had  reen- 
forced-concrete  floors  with  furred  ceilings  and  partitions  of  metal 
lath  and  plaster.  The  window  frames  and  sash  were  metal  covered, 
and  there  was  very  little  combustible  matter  in  the  finish.  The 
doors,  with  their  frames  and  jambs,  were  of  wood  covered  with 
sheet  metal.  It  is  manifest  that  this  building  was  not  subjected  to 
very  intense  heat,  as  the  windows  above  the  fourth  story  were 
unbroken  and  the  stone  was  comparatively  undamaged.  The  first, 
second,  and  third  stories  were  burned  out,  and  there  was  some  damage 
in  both  the  fourth  story  and  the  attic. 

The  metal-covered  doors  in  this  building,  however,  prevented  to 
some  extent  the  spread  of  the  fire  within  the  building  itself,  so  that 
where  one  room  burned  out,  the  fire  coming  in  through  a front 
window,  an  adjacent  room  was  not  burned  because  of  the  resistance 
offered  by  the  door.  The  building  could  hardly  have  been  sub- 
jected to  a very  fierce  heat,  however,  for,  if  it  had  been,  the  light 
partitions  would  have  failed,  in  which  case  the  metal-covered  doors 
would  have  been  of  no  avail.  Where  the  heat  was  really  intense, 
the  wood  of  doors,  frames,  and  windows  burned  out  under  the  metal 
anyway,  but  of  course  the  metal  covering  delayed  the  ignition  of 
the  wood  a lid  later  prevented  it  from  burning  freely. 

merchants’  exchange  building. 

The  structure  known  as  the  Merchants’  Exchange  was  a steel- 
frame  building  with  Roebling  cinder-concrete  flat  floor  slabs,  double 
wire-lath  and  plaster  protection  for  the  columns,  and  partitions 
made  of  light  furring  irons,  wire  lath,  and  plaster.  In  some  places 
wire  lath  and  plaster  were  applied  to  both  sides  of  the  furring 
strips;  in  others  the  furring  strips  with  the  wire  lath  were  simply 
plastered  on  both  sides.  This  was  one  of  the  buildings  in  which 
the  vault  walls  were  made  of  the  same  materials  as  the  partitions. 
Every  vault  in  the  building  failed.  All  the  partitions  in  the  build- 
ing were  a total  loss;  not  only  did  the  plaster  have  to  come  off,  but 
the  metal  framework  had  to  come  down  also.  The  floor  construc- 
tion had  a furred  ceiling  below  it.  The  plaster  had  come  down 
because  of  the  heat  on  nearly  all  the  ceilings,  and  probably  as  much 
as  20  per  cent  of  the  furring  rods  and  wire  lathing  were  down. 

Large  areas  of  the  face  bricks  were  shaken  from  the  wall  of  this 
building,  owing  to  the  fact  that  they  were  laid  without  bond.  The 
rear  wall  was  also  damaged  by  the  earthquake.  The  adhesion  of  the 
bricks  and  mortar  seemed  to  be  largely  destroyed  throughout  the  wall, 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


95 


without,  however,  producing  any  very  large  cracks.  It  is  doubtful 
whether  the  wall  is  really  safe  in  its  present  condition.  On  the  inside 
of  this  building  some  of  the  wall  columns  were  covered  with  4 inches 
of  brickwork  projecting  from  the  inner  face  of  the  wall  as  a pilaster. 
Some  of  these  brick  coverings  had  cracked  almost  entirely  away  from 
the  main  walls,  besides  being  cracked  vertically  at  other  points  in  a 
manner  similar  to  the  cinder-concrete  column  coverings  in  the  base- 
ment of  the  Aronson  Building  described  on  page  T9.  The  brickwork 
in  these  places  seemed  to  have  been  rather  below  the  average  in 
quality.  It  is  not  entirely  certain  whether  the  fire  or  the  earthquake 
caused  the  cracks,  but  all  the  columns  seem  to  have  been  uninjured, 
although  the  brickwork  of  one  or  two  was  so  badly  damaged  that  it 
ought  to  be  taken  down  and  rebuilt.  Some  enameled  bricks  were 
practically  ruined  by  the  fire,  which  stripped  off  the  enamel  face 
(PI.  XL,  A). 

MILLS  BUILDING. 

The  large  steel- frame  Mills  Building  was  without  special  bracing. 
The  floors  were  of  hollow  tiles  on  the  end-construction  system,  and  the 
remainder  of  the  fireproofing  was  likewise  of  hollow  tiles.  The  tile 
arches  lost  their  lower  webs  to  a great  extent,  and  some  of  them 
collapsed,  apparently  from  heat  alone;  the  column  coverings  failed 
very  generally,  and  the  girder  coverings  to  a somewhat  less  extent 
(PL  XLV,  B).  One  basement  column  buckled  under  the  action  of 
the  heat  (PI.  XL,  B).  The  conditions  in  the  Mills  Building  as  to 
column  coverings  and  partitions  were  similar  to  those  in  the  Aronson 
Building. 

UNITED  STATES  MINT. 

The  mint  was  an  old-fashioned  monumental  structure  with  granite 
walls  and  segmental  brick-arch  floor  construction,  ' carried  on  iron 
beams.  A general  view,  showing  the  southwest  front,  is  presented  in 
PI.  XXXVIII,  A.  The  building  seems  to  have  been  practically 
uninjured  by  the  earthquake,  the  only  damage  visible  being  at  the 
base  of  the  right-hand  brick  stack.  It  is  probable  that  the  shock  at 
the  locality  of  the  mint  was  not  so  severe  as  it  was  at  the  new  post-office 
building,  although  the  two  are  only  a few  blocks  apart ; yet  the  result 
may  be  an  indication  that  the  solid  old-fashioned  monumental  walls 
with  the  stonework  solidly  backed  up  by  brickwork  constitute  after 
all  one  of  the  best  types  for  resisting  earthquake  shocks. 

It  is  somewhat  surprising  that  the  brick  stacks  were  not  over- 
thrown, but  I am  informed  that  the  thickness  of  the  masonry  in  these 
stacks  was  very  great,  which  probably  explains  their  stability.  The 
northwest  (PI.  XXXVIII.  B)  and  northeast  faces  of  the  mint  were 


96 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


considerably  damaged  by  the  fire,  but  the  fire  was  kept  out  of  the 
building  proper  by  means  of  water  from  an  artesian  well  equipped 
with  fire  pumps,  located  in  the  building. 

MONADNOCK  BUILDING. 

The  structure  known  as  the  Monadnock  Building  was  an  ordinary 
steel-frame  office  building,  which  was  in  process  of  erection.  It  was 
badly  racked  by  the  earthquake.  Every  one  of  the  piers  in  which 
the  earthquake  cracks  appeared  was  so  badly  shattered  that  no  re- 
pairs short  of  tearing  down  and  rebuilding  would  suffice.  As  a 
matter  of  fact,  it  is  probable  that  adequate  repairs  to  the  masonry  in 
the  front  wall  of  this  building  would  involve  reconstructing  more 
than  half  of  it.  It  would  appear  that  there  must  have  been  rather 
severe  vibration  to  shatter  the  brickwork  so  badly.  Whether  the 
steel  escaped  injury  is  a question  of  considerable  interest,  which  can 
not  be  settled  until  the  masonry  covering  is  taken  off. 

MUTUAL  LIFE  BUILDING. 

The  Mutual  Life  Building  was  a steel-frame  structure  of  the 
same  general  type  as  the  Mills  Building,  and  it  suffered  in  the  same 
general  way,  though  possibly  not  quite  so  much.  Some  of  the  floor 
arches  had  collapsed,  apparently  from  falling  weights  of  some  sort. 
(See  PI.  XLII,  A.) 

PACIFIC  STATES  TELEPHONE  AND  TELEGRAPH  BUILDING. 

The  Pacific  States  Telephone  and  Telegraph  Building,  on  Bush 
street,  illustrated  the  tendency  of  the  earthquake  to  shear  off  project- 
ing pilasters  (PI.  XLI,  A).  This  building  had  a steel  frame,  stone- 
concrete  floor  arches,  furred  ceilings  above  the  basement,  and  con- 
crete column  and  girder  coverings.  The  front  windows  were  of 
plate  glass  in  metal-covered  sash,  with  rolling  steel  shutters  on  the 
outside.  The  side  and  rear  windows  were  of  wire  glass  in  metal- 
covered  sash  and  frames,  with  sliding  tin-covered  wooden  shutters  on 
the  inside. 

The  window  protection  seems  to  have  prevented  the  entrance  of 
fire  from  the  outside,  but  in  some  other  way  an  interior  fire  was 
started  which  completely  gutted  the  building.  The  interior  fire 
practically  destroyed  the  plate  glass,  but  not  the  rolling  steel  shutters. 
It  seriously  damaged  the  tin-clad  shutters,  but  did  not  damage  the 
wire  glass  appreciably.  Had  the  interior  fireproofing  been  as  effi- 
cient as  the  window  protection  it  is  doubtful  whether  this  building 
would  have  been  burned  out,  for  the  interior  fire  should  have  been 
confined  to  the  place  of  its  origin.  For  these  probable  facts  as  to  the 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


97 


history  of  the  fire  in  this  building  I am  indebted  to  S.  A.  Reed,  con- 
sulting engineer  for  the  committee  of  twenty  of  the  National  Board 
of  Fire  Underwriters.  Mr.  Reed  states,  however,  that  the  history  of 
the  fire  here  must  be  largely  surmise,  because  reliable  evidence  Avas 
not  obtainable. 

This  company  had  also  a building  with  reenforced-concrete  floor 
construction  and  wire-glass  protection  for  its  windows  for  one  of  its 
branch  exchanges.  The  exposure  of  this  building  was  probably  not 
very  severe.  It  was  three  stories  high  and  the  fire  got  into  the  upper 
story  and  cleaned  it  out ; but  the  floor  construction  prevented  the  fire 
from  extending  into  the  stories  below,  which  suffered  practically  no 
damage  to  structure  or  contents.  A part  of  the  third-story  Avail 
Avas  throAvn  down  either  by  the  earthquake  or  by  some  other  means, 
and  this  damage  may  have  opened  a way  for  the  entrance  of  the  fire. 

PALACE  HOTEL. 

All  of  the  interior  and  the  exterior  walls  of  the  Palace  Hotel,  on  the 
south  side  of  Market  street,  were  built  of  brickwork.  It  is  reported 
that  the  brickwork  Avas  reenforced  with  embedded  iron  bars.  The 
structure  stood  remarkably  well,  and  there  is  little  indication  of 
earthquake  damage.  The  building  was  nonfireproof,  and  was,  of 
course,  completely  burned  out,  but  the  walls  still  stand  almost  as  good 
as  ever.  (See  PI.  XXX,  B.) 


POST-OFFICE  BUILDING. 

The  steel-frame  and  granite  post-office  building  (Pis.  XLII,  B\ 
XLIII;  XLIV)  was  carried  on  isolated  grillage  foundations,  each 
column  having  its  own  footing.  The  diagonals  of  the  building  ran 
nearly  north  and  south  and  east  and  west,  the  south  corner  being  at 
Seventh  and  Mission  streets.  To  the  south  and  west  of  Mission 
street  was  an  elongated,  narrow,  curved  area  in  Avhich  the  earth- 
quake damage  was  very  severe.  It  was  commonly  reported  that  this 
area,  which  was  not  far  from  the  south  corner  of  the  post-office  build- 
ing, was  a stream  bed  or  ravine  that  had  been  filled  within  the 
recollection  of  the  older  inhabitants  of  San  Francisco.  Through  the 
courtesy  of  J.  W.  Roberts,  the  local  representative  of  the  Supervising 
Architect’s  Office  of  the  Treasury  Department,  I was  enabled  to  make 
a detailed  inspection  of  the  building,  and  he  also  gave  me  very  com- 
plete information  as  to  the  history  of  the  building  and  the  causes 
of  the  various  items  of  damage  which  were  in  evidence  at  the  time 
of  my  inspection.  Mr.  Roberts,  who  is  evidently  a cool  and  accu- 
rate observer,  seemed  of  the  opinion  that  the  material  under  the 
building  Avas  a natural  deposit,  and  not  an  artificial  fill.  But  toward 


98  THE  SAN-  FRANCISCO  EARTHQUAKE  AND  FIRE. 

the  south  it  was  not  of  a nature  to  inspire  confidence  in  its  carrying 
power  at  the  depth  shown  on  the  foundation  plans.  He  accordingly 
obtained  authority  to  lower  the  footings  wherever  the  material  at 
the  depth  shown  on  the  plans  seemed  unreliable,  so  that  the  footings 
of  the  south  half  of  the  building  were  lowered — some  of  them,  as  I 
remember  his  statements,  to  a depth  of  20  feet  or  more  below  the 
basement-floor  level.  At  any  rate,  he  carried  them  to  a point  where 
the  material,  in  his  judgment,  was  sufficiently  hard  and  compact.  All 
this  underlying  material  is  very  sandy ; but  at  considerable  depths,  I 
understand,  gravel  appears,  and  the  combination  is  almost  as  hard 
as  hardpan. 

The  walls,  floors,  and  all  parts  of  the  post-office  building  proper 
are  carried  on  the  steel  frame.  The  outer  walls  consist  of  a granite 
facing,  carried  on  the  steel  work  at  each  floor  level.  The  granite  is 
not  backed  up  in  the  usual  way,  the  backing  having  been  omitted 
to  save  weight.  Some  distance  behind  the  granite  an  inner  wall  was 
built  of  hollow  terra-cotta  blocks.  The  space  between  the  granite 
and  the  terra  cotta  was  used  for  the  passage  of  pipes,  air  flues,  etc. 
The  granite  was  heavily  anchored  to  the  steel  work.  In  a number 
of  panels  of  the  steel  work  corner  braces  made  of  a pair  of  channels 
were  used,  and  they  were  fastened  as  far  down  on  the  columns  and 
as  near  to  the  center  of  the  wall  girder  that  spanned  the  space 
between  the  columns  as  the  window  openings  would  permit.  There 
was  also  some  portal  bracing  in  a part  of  the  building  over  which 
it  had  been  intended  to  erect  a tower.  This  intention  was  afterwards 
abandoned,  but  I understand  the  bracing  was  in  place.  In  a general 
way,  panels  of  the  outer  wall  in  which  the  corner  bracing  was  used 
suffered  less  than  adjacent  panels — especially  in  projecting  pavilions, 
where  there  was  no  bracing. 

Practically  all  the  interior  walls  of  the  building  above  the  base- 
ment were  built  of  hollow  tiles.  The  tiles  were  of  excellent  quality, 
with  webs  nearly  1 inch  thick.  The  floor  and  roof  construction  was 
of  clinker  concrete,  reenforced  with  expanded  metal.  Suspended 
ceilings  of  metal  lath  and  plaster  were  very  generally  used.  In  the 
mail-handling  room  there  were  a number  of  isolated  columns  filled 
solid  with  clinker  concrete  and  covered  with  4 inches  of  enameled 
brickwork.  The  column  covering  was  circular,  the  bricks  having 
been  made  radial  for  this  purpose. 

The  lower  part  of  the  column,  however,  was  incased  in  a circular 
cast-iron  covering  made  in  halves  and  put  together  around  the  col- 
umn. This  casing  took  the  place  of  the  enameled  brick  up  to  a 
point  above  which  injury  from  blows  and  abrasion  was  not  likely  to 
occur.  There  were  also  in  the  mail-handling  room  a number  of 
circular  shafts  of  enameled  brickwork,  with  stairways  inside,  leading 
to  the  inspectors’  galleries.  The  corridors  of  the  building  and  the 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


99 


more  important  rooms  had  a great  deal  of  expensive  and  beautiful 
marble  finish;  there  was  much  marble-mosaic  ceiling  work,  and  the 
finished  woodwork  was  off  extraordinary  richness.  On  top  of  the 
buildings  were  a number  of  chimneys  built  of  granite  blocks  with 
terra-cotta  linings. 

All  the  materials  entering  into  the  construction  and  finish  of  this 
building  were  the  best  of  their  kind,  and  the  workmanship,  under 
the  efficient  supervision  of  Mr.  Roberts,  was  as  nearly  perfect  as  it  is 
possible  to  make  it.  I have  never  seen  work  better  done,  and  have 
rarely  seen  it  so  well  done.  To  one  who  knows  and  appreciates  good 
work  it  is  a continual  pleasure  to  see  everywhere  in  the  San  Fran- 
cisco post-office  the  record  of  sleepless  vigilance  and  skilled  labor. 
Where  the  structural  parts  were  laid  bare  by  the  damage  due  to  the 
earthquake,  the  same  story  was  told  by  the  minutest  details  as  well 
as  the  roughest  parts  of  the  work — everything  was  the  best  of  its 
kind.  It  is  therefore  of  great  interest  to  study  the  effect  of  the 
earthquake  on  this  structure,  for  the  care  with  which  it  was  built 
must  have  made  it  fully  as  good  as  its  designers  could  have  hoped. 
Moreover,  I am  inclined  to  think  that  it  received  a more  severe  shak- 
ing than  any  other  building  in  the  congested  district  of  San  Fran- 
cisco that  was  at  all  comparable  with  it.  The  city  hall  was  badly 
racked,  but,  to  judge  from  the  condition  of  the  adjacent  street  sur- 
faces and  the  surrounding  ruins,  the  shock  was  much  less  severe  than 
that  to  which  the  post-office  was  subjected.  For  instance,  there  was 
a partially  erected  steel  frame  (PL  XLII,  B)  on  the  southwest  side 
of  Seventh  street,  near  the  post-office.  Before  the  earthquake  all  the 
columns  were  plumb  and  in  true  alignment.  As  a result  of  the  shock 
there  was  a lateral  shifting  of  the  column  bases — the  relative  move- 
ment being  almost  2 feet  in  some  places— at  the  cellar-floor  level. 
The  basement  walls  of  the  incomplete  building  were  also  shifted 
horizontally;  at  the  east  corner,  where  the  walls  had  met  at  a right 
angle,  they  had  been  ruptured  by  a vertical  crack  and  moved  laterally 
in  such  a way  that  the  angle  between  them  was  reduced  to  about  75°, 
as  nearly  as  I could  estimate  it  without  taking  measurements. 

The  south  corner  of  the  post-office  building  is  shown  in  PL  XLIY, 
A.  Mr.  Roberts  states  that  accurate  measurements  show  that  the 
building  proper  settled  a little  at  this  point,  but  not  more  than  one- 
eighth  inch  relative  to  other  parts  of  the  structure.  The  general 
appearance  of  the  building  bears  out  this  statement.  The  result  is 
remarkably  gratifying  when  the  great  extent  of  the  near-by  surface 
disturbance  on  Mission  street  is  considered.  The  street  went  down 
about  4 or  5 feet  at  this  point  as  a result  of  the  earthquake  (Pl. 
XLIII,  B).  The  molded  granite  shelf  surrounding  the  building, 
shown  with  small  timber  props  under  it  in  PL  XLIY,  A , was  set  into 
a rebate  in  the  main  wall  of  the  building.  When  the  sidewalk  and 


100 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


the  supporting  granite  curb  settled  away  from  the  shelf,  it  remained 
in  position,  as  a cantilever,  but  the  props  were  put  under  it  to  keep  it 
from  being  broken.  In  the  basement  no  evidence  of  the  earthquake 
could  be  found,  except  a few  insignificant  cracks  in  the  concrete  floor, 
which  Mr.  Roberts  says  were  not  there  before  the  earthquake. 

On  the  whole,  I think  it  is  fair  to  say  that  the  post-office  was  sub- 
jected to  an  extraordinarily  severe  test.  About  half  of  the  chimneys 
were  thrown  down.  One  of  them  either  rocked  on  its  base  or  was 
thrown  upward  far  enough  to  cause  the  counterflashing,  which  lapped 
the  flashing  about  3 inches,  to  clear  the  flashing  and  come  down  inside 
of  it.  The  chimney  remained  upright,  but  with  a slight  horizontal 
displacement.  In  the  exterior  walls  a good  many  stones  were  started 
from  their  beds,  and  some  were  cracked.  Two  or  three  fell  from  the 
wall.  At  least  one  anchor  was  exposed,  and  it  had  been  broken. 
Whether  the  steel  work  was  damaged  or  not  could  not  be  determined, 
as  it  was  not  sufficiently  exposed.  The  damage  to  the  exterior  walls  is 
fairly  well  shown  in  Pis.  XLIII,  A,  and  XLIV. 

PI.  XLIII,  A,  shows  damage  on  the  southwest  side  of  the  west 
corner  of  the  building;  the  surface  of  the  window  reveal  and  the 
adjacent  return  of  the  upper  molding  on  the  sill,  at  the  point  indi- 
cated by  the  arrow,  were  separated  at  least  three-fourths  of  an  inch, 
yet  during  the  earthquake  they  were  jostled  together  with  sufficient 
force  to  abrade  the  reveal  and  spall  the  sill.  That  this  effect  should 
have  taken  place  without  shattering  all  the  masonry  around  the  win- 
dow opening  is  one  of  the  many  inexplicable  phenomena  that  seem 
characteristic  of  earthquakes. 

The  two  sides  of  the  pavilion  on  the  Mission  street  side  at  the 
east  corner  showed  cracks  in  the  masonry  and  a disturbance  of  the 
sidewalk.  A window  arch  on  the  northeast  front,  where  the  outer 
wall  of  the  mail-handling  room  adjoins  the  main  building,  was 
damaged  (PI.  XLIV,  B ).  The  building  is  U-shaped  in  plan,  the 
mail-handling  room  being  in  the  court  and  closed  in  on  the  northeast 
by  a wall.  This  wall  was  seriously  shaken  and  was  shored  up  at 
the  time  of  my  inspection. 

With  the  exception  of  one  window  at  the  north  corner,  the  exterior 
masonry  of  the  building  practically  escaped  damage  from  the  fire. 
According  to  Mr.  Roberts,  the  damage  on  the  northwest  front  was 
somewhat  increased  after  the  fire  as  a result  of  the  demolition  of 
some  neighboring  walls  by  dynamite  because  of  their  dangerous 
condition. 

On  the  interior  some  of  the  marble  slabs  used  for  dadoes  and  wall 
coverings  were  shaken  off  by  the  earthquake,  and  some  marble  col- 
umns used  in  connection  with  ornamental  mantels  and  doorways  were 
thrown  down. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


101 


A great  many  marble  slabs  were  thrown  down  by  the  concussion 
due  to  the  dynamiting  of  dangerous  walls  at  Seventh  and  Market 
streets,  less  than  half  a block  away.  The  damage  to  marble  finish 
from  this  cause  was  much  greater  than  that  due  to  the  earthquake. 
Although  the  slabs  brought  down  by  the  dynamite  may  have  been 
loosened  by  the  earthquake^  they  could  have  been  taken  down  and 
reset  if  the  dynamite  had  not  caused  their  total  loss.  In  one  sense 
much  of  the  loss  was  irreparable,  for  adjacent  slabs  were  beautifully 
matched  by  being  sawed  from  the  same  block  and  then  so  set  in 
groups  of  two  or  four  that  the  veining  was  symmetrical  about  the 
joints.  Where  one  slab  of  a group  was  destroyed  the  only  way  to 
restore  the  finish  to  its  original  beauty  would  be  to  renew  the  whole 
group.  In  addition  to  injuring  the  marble  finish,  the  dynamite  did 
much  damage  by  blowing  windows,  transoms,  and  doors  from  their 
frames,  and  by  blowing  panels  out  of  doors  and  glass  out  of  windows. 
With  the  kind  of  woodwork  used  in  this  building  and  with  plate 
glass  in  all  the  windows,  this  item  of  damage  was  very  heavy. 
Debris  from  the  demolished  buildings,  also,  was  thrown  across  the 
street  and  came  down  through  one  or  two  skylights  in  the  post-office 
building.  It  was  only  owing  to  good  luck  that  some  of  the  employees 
were  not  killed  or  seriously  injured.  As  it  was,  the  interiors  of  one  or 
two  expensively  finished  rooms  were  almost  wrecked.  All  the  items 
of  damage  which  Mr.  Roberts  ascribed  to  the  dynamite  were  of  the 
same  general  type  as  those  due  to  the  concussion  in  mortar  batteries,  etc. 
The  chief  engineer  of  the  building  stated  that  he  and  some  of  his 
subordinates,  although  down  in  the  basement,  were  thrown  to  the 
floor  by  the  force  of  one  of  the  dynamite  explosions,  and  that  the 
electric  lights  were  extinguished  for  several  seconds,  although  the 
engines  kept  running.  Probably  the  concussion  lifted  the  brushes 
from  the  commutators  of  the  generators.  It  seems  probable,  from 
what  evidence  I was  able  to  gather,  that  at  first  the  dynamite  was 
used  in  rather  large  quantities  without  tamping;  but  later  it  was 
used  in  a more  tentative  way  and  tamped  with  sand  bags.  By  this 
policy  those  in  charge  of  the  later  blasting  operations  finally  got 
the  work  down  to  a system  whereby  a wall  was  brought  down  within 
a distance  of  20  feet  from  the  base  on  either  side  without  any  dan- 
gerous hurling  of  debris  beyond  that  distance.  So  far  as  I was 
able  to  learn,  after  the  work  had  reached  this  stage  no  one  noticed 
any  damage  to  neighboring  structures,  and,  in  fact,  very  few  people 
were  aware  that  blasting  was  in  progress.  # 

Some  of  the  mosaic  ceilings  in  the  post-office  building  were  planted 
on  a terra-cotta  base,  others  on  a furring  of  metal  lathing  and  plas- 
ter. The  former  were  seriously  damaged  by  the  earthquake,  but 
the  latter  remained  intact.  As  previously  stated,  the  interior  walls 
7171— Bull.  324—07 8 


102 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


in  the  post-office  were  built  of  6-inch  terra-cotta  blocks,  with  webs 
nearly  1 inch  thick.  They  were  beautifully  built,  every  joint  being 
absolutely  tilled  with  cement  mortar  that  was  much  harder  than 
the  tiles,  though  the  latter  were  of  exceptionally  good  quality.  None 
of  these  walls  were  thrown  down,  but  many  of  them  showed  the 
intersecting  diagonal  cracks  that  are  characteristic  of  earthquake 
action.  The  tiles  along  the  lines  of  the  cracks  were  so  badly  shat- 
tered that  many  of  them  will  have  to  come  out.  As  a contrast, 
reference  is  made  to  PI.  XL VI,  B , showing  earthquake  damage  to 
good  brickwork.  In  the  tile  wall  the  same  cracks  appear,  but  the 
tiles  are  badly  shattered  for  some  distance  on  either  side.  In  addi- 
tion, in  much  of  the  flimsy  tile  work  in  the  commercial  buildings 
the  adhesion  of  the  mortar  in  the  entire  partition,  if  there  was  any, 
was  destroyed.  In  the  concrete  walls  at  Palo  Alto  a few  cracks  ap- 
peared here  and  there  as  a result  of  the  earthquake;  but  they  were 
even  sharper  and  narrower  than  the  crack  shown  in  PI.  XL VI,  B , 
and  there  was  no  shattering  effect  whatever. 

The  column  coverings  in  the  mail-handling  room,  described  above, 
were  absolutely  uninjured,  but  the  circular  brick  walls  around  the 
spiral  stairways  developed  many  rather  ugly  spiral  cracks.  Such 
cracks  were  very  conspicuous  also  in  circular  smokestacks,  where  the 
damaged  work  was  not  throwm  down  entirely. 

The  floor  construction  in  the  post-office  was  absolutely  undamaged 
by  the  earthquake.  This  was  one  building  where  u cinder  concrete  ” 
was  made  as  it  should  be — of  well-burned  clinker  only.  In  the  court 
room  which  burned  out  a part  of  the  furred  ceiling  came  down,  ex- 
posing the  floor  slab  above.  It  may  not  have  received  a very  severe 
test,  for  when  work  is  done  as  well  as  it  was  in  this  building  even  a 
furred  ceiling  will  exhaust  the  fury  of  a fairly  hot  fire.  Be  that  as  it 
may,  the  floor  slab  showed  no  signs  of  damage  whatever,  and  it  was 
the  only  case  I saw  where  the  heat  had  evidently  reached  the  floor 
slab  without  leaving  some  degree  of  damage  behind.  The  fire  did 
not  get  through  the  6-inch  hollow-tile  walls  either,  and  it  took  off 
very  few  exposed  webs.  Here  again  it  is  probable  that  the  plaster 
finish  was  so  well  done  that  it  prevented  the  tiles  from  getting  the  full 
effect  of  the  fire.  The  fire  was  stopped  at  the  entrance  to  another 
court  room,  where  there  was  a double  wooden  door,  consisting  of 
one  door  on  each  side  of  the  partition.  Water  and  wet  blankets 
sufficed  to  stop  the  fire  at  this  point,  and  it  is  reasonable  to  suppose 
tha^the  extra  resistance  of  a second  door,  even  though  it  was  of 
wood,  was  a material  factor  in  the  result.  From  a purely  technical 
point  of  view  it  is  to  be  regretted  that  the  post-office  building  was  not 
more  seriously  involved  in  the  fire,  for  its  fireproofing  was  of  a com- 
mercial type — in  its  best  possible  form,  however.  Such  a test  would 
have  yielded  more  interesting  results  than  all  the  rest  of  San  Fran- 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


103 


cisco  combined.  It  is  my  personal  opinion  that  the  results  would 
have  indicated  to  private  owners  the  availability  of  a desirable  form 
of  fire  insurance  at  moderate  cost  on  which  but  one  premium  would 
have  to  be  paid. 

The  post-office  building  was  so  carefully  and  intelligently  designed 
and  so  well  executed,  and,  all  things  considered,  gave  so  good  an 
account  of  itself,  that  it  seems  a little  presumptuous  to  suggest 
wherein  it  could  be  made  better.  Yet  I believe  that  if  the  granite 
had  been  solidly  backed  with  good  brickwork  and  even  more  heavily 
anchored  to  the  steel  frame,  if  the  frame  had  been  more  completely 
and  heavily  braced,  and  if  all  the  interior  partitions  had  been  of 
solid  brickwork,  the  structural  damage  would  have  been  much  less; 
and  even  the  greater  weight  on  the  foundations  might  have  been  an 
advantage  rather  than  otherwise.  Mr.  Roberts  estimates  the  total 
damage  as  about  $400,000.  Of  this  damage  more  than  one-fourth, 
much  of  which  was  caused  by  the  dynamite,  is  charged  to  marble 

finish  and  plate  glass.  The  cost  of  the  building  was  about  $2,500,000. 

I 

RIALTO  BUILDING. 

The  Rialto  Building  was  a steel-frame  structure,  with  expanded- 
metal  and  cinder-concrete  slabs,  expanded-metal  and  plaster  column 
covering,  and  furred  expanded-metal  ceiling.  It  had  two  main  wings, 
in  each  of  which  it  is  said  attempts  were  made  to  dynamite  the  build- 
ing, the  explosions  causing  the  collapse  of  a portion  of  the  interior 
structural  work.  A hole  in  the  roof  was  produced  by  the  same  cause. 
PL  XL VIII,  R,  a view  of  the  southeast  corner  of  the  building,  shows 
a portion  of  this  damage  at  close  range,  and  is  submitted  to  show  the 
effect  of  dynamite  on  a steel- frame  building. 

The  fact  that  the  building  was  dynamited  makes  it  impossible  to 
draw  any  useful  conclusions  as  to  its  fire-resisting  qualities ; but  there 
seems  to  have  been  only  a moderately  hot  fire  in  this  building,  and  the 
fireproofing,  while  seriously  damaged,  was  not  a total  failure  as  a 
result  of  the  fire  alone.  The  north  front  was  badly  racked  by  the 
earthquake,  resulting  in  many  cracks  in  the  walls.  The  south  front 
of  this  building  was  also  damaged  by  the  earthquake ; the  intersecting 
diagonal  cracks  in  the  walls  were  plainly  visible.  A considerable 
amount  of  face  brickwork  was  thrown  off  on  this  front,  probably 
owing  to  the  fact  that  it  was  laid  without  bond. 

ST.  FRANCIS  HOTEL. 

The  new  St.  Francis  Hotel,  which  had  been  occupied  but  a short 
time,  had  a sandstone  front  and  was  supported  by  columns  pro- 
tected with  cinder  concrete.  These  columns  were  entirely  undam- 
aged, although  a section  near  the  upper  end  of  each  column  which 


104  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

had  apparently  been  covered  in  by  a furred  beam,  or  other  archi- 
tectural feature,  since  destroyed,  was  entirely  devoid  of  protective 
covering.  A great  many  people  in  San  Francisco  regarded  the 
behavior  of  these  columns  as  a substantial  recommendation  of  cinder 
concrete,  but  the  whole  building  bears  evidence  of  having  been  sub- 
jected to  only  a moderate  heat. 

SHREVE  BUILDING. 

The  columns  in  the  first  and  second  stories  of  the  Shreve  Building 
were  covered  with  cinder  concrete;  those  in  the  upper  stories  with 
hollow  tiles.  All  the  evidence  in  this  building  points  to  a moderate 
heat.  The  plastering  on  the  columns  was  not  seriously  damaged, 
and  such  plastering  never  stands  an  intense  heat.  The  hollow  tiles 
on  the  columns  came  off  very  generally,  but  it  is  probable  that  the 
heat  was  more  intense  in  the  upper  portion  of  the  building  than  in 
the  lower  portion.  This  theory  is  supported  by  the  fact  that  the 
damage  to  the  masonry  adjacent  to  the  windows  was  most  severe  in 
the  upper  stories. 

This  building,  like  the  St,  Francis  Hotel,  is  cited  as  an  example 
of  the  excellent  behavior  of  cinder  concrete  as  a column  covering, 
but  in  this  case  also  there  is  every  reason  to  believe  that  the  con- 
crete did  not  receive  a severe  test.  The  only  cinder-concrete  cover- 
ing I saw  that  had  evidently  received  an  extreme  test  was  in  the 
basement  of  the  Aronson  Building,  as  described  on  page  79. 

SLOANE  BUILDING. 

The  mercantile  structure  known  as  the  Sloane  Building,  at  114 
Post  street,  had  cast-iron  columns,  protected  with  expanded  metal 
and  plaster.  The  floor  slabs  were  of  expanded  metal  and  cinder 
concrete.  The  basement  of  this  building  was  subjected  to  an  ex- 
tremely fierce  heat.  At  least  six  or  eight  of  the  columns  had  their 
covering  destroyed,  and  the  columns  themselves  either  buckled  or 
failed  to  such  an  extent  that  a large  portion  of  the  framework  above 
was  knocked  down  afterwards  as  a matter  of  safety.  In  the  rear 
of  the  basement  two  rows  of  columns  across  the  entire  width  of 
the  building  had  practically  all  failed  in  the  same  way,  but  the 
debris  was  piled  around  them  to  such  an  extent  that  views  could 
not  be  obtained. 

SPRING  VALLEY  WATER  COMPANY’S  BUILDING. 

The  Spring  Valley  Water  Company’s  Building,  at  Post  and  Geary 
streets,  was  used  for  office  purposes  in  the  upper  stories  and  for  mer- 
cantile purposes  in  the  first  and  second  stories.  The  southeast  corner 
had  totally  collapsed  (PI.  L,  A),  apparently  from  the  failure  of  the 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


105 


basement  or  first-story  columns  under  the  action  of  the  heat.  PI. 
XLV,  A,  is  a view  taken  in  the  first  story  of  this  building,  which  had 
been  occupied  by  the  City  of  Paris  Dry  Goods  Company.  This  view 
is  submitted  as  illustrating  a typical  but  rather  bad  example  of  the 
loss  of  lower  webs  from  hollow-tile  floor  arches.  The  column  cover- 
ings shown  in  the  view  had  suffered  about  as  little  as  any  others. 
The  coverings  of  other  columns  in  the  same  building  were  practically 
destroyed,  as  were  also  the  partitions.  The  same  sort  of  damage  as 
that  shown  in  PI.  XLV,  X,  was  plainly  visible  in  some  of  the  upper 
stories  of  this  building,  especially  the  second  story. 

A stairway  carried  on  unprotected  cast-iron  strings  was  destroyed 
by  the  heat  in  this  building.  The  same  thing  occurred  in  a number 
of  other  buildings  in  San  Francisco,  even  where  the  stairways  had 
been  walled  off  by  hollow-tile  partitions  or  by  partitions  made  of 
light  studs,  metal  lathing,  and  plaster.  It  has  generally  been  con- 
sidered— in  commercial  work,  at  any  rate — unnecessary  to  protect  a 
stairway  carried  on  cast-iron  strings,  but  the  San  Francisco  fire 
showed  that  some  form  of  protection  is  very  essential.  Where  the 
inclosing  partitions  did  not  fail,  the  stairways  were  of  course  not 
seriously  damaged,  but  as  a matter  of  fact  the  partitions  failed 
almost  everywhere  in  San  Francisco. 

UNION  FERRY  BUILDING. 

The  Union  Ferry  Building  (PI.  XLVI,  A)  is  a large  structure — ■ 
practically  of  monumental  proportions — which  forms  the  terminus  of 
all  the  ferry  lines  plying  between  San  Francisco  and  various  other 
points  on  the  bay.  It  is  built  on  piles,  with  heavy  stone  walls,  backed 
with  brickwork.  The  stone  is  the  gravish-green  sandstone  elsewhere 
described.  The  floor  construction  consists  of  steel  beams  and  girders, 
with  stone-concrete  slabs  reenforced  with  expanded  metal.  The  lower 
flanges  or  girders  and  beams  were  not  protected.  Xear  the  center  of 
the  west  front  a high  tower  rises  to  a considerable  distance  above  the 
building.  The  fire  did  not  gain  entrance,  but  the  building  was  very 
seriously  racked  and  damaged  by  the  earthquake.  The  damage  was 
not  at  all  of  a fatal  nature,  however,  and  the  building  was  kept  in 
practically  continuous  operation  as  a ferry  terminus.  The  tower, 
which  was  built  with  a braced  steel  frame,  inclosed  to  a height  of 
several  stories  with  a heavy  wall  composed  of  sandstone  backed  with 
brick,  and  closed  in  with  wood  and  sheet  metal  above  the  masonry 
part,  was  so  badly  damaged  that  the  masonry  walls  were  being 
removed  at  the  time  of  my  inspection.  To  judge  by  the  effects  on  this 
tower,  the  greatest  intensity  of  the  earthquake  vibration  must  have 
been  from  northwest  to  southeast.  The  bracing  was  badly  strained, 


106  THE  SAN  FEAN CISCO  EAKTHQUAKE  AND  FIEE. 

and  in  this  case  there  can  be  no  question  that  the  effect  was  entirely 
due  to  the  earthquake.  The  masonry  in  the  tower  was  of  an  admira- 
ble quality. 

In  PL  XL VI,  B , is  shown  a crack  in  the  brick  masonry  on  the 
inside  of  the  tower,  together  with  a part  of  a diagonal  tie-rod  which 
had  been  stretched  beyond  the  elastic  limit  and  was  hanging  with  a 
noticeable  sag.  It  will  be  noted  that  the  brickwork  was  well  bonded 
and  that  the  joints  were  well  filled.  The  mortar  was  much  harder 
than  the  bricks,  but  both  were  of  good  quality.  It  is  also  evident 
from  this  view  that  there  was  no  general  shattering  of  the  entire 
mass ; there  was  a well-defined  crack,  but  nothing  else. 

At  the  northwest  corner  of  the  tower,  about  halfway  from  the  roof 
of  the  main  building  to  the  top  of  the  masonry  walls  of  the  tower,  a 
diagonal  tie-rod  had  been  fastened  to  the  wall  girder  by  means  of  a 
gusset  plate,  with  eight  rivets  in  it.  Seven  of  these  rivets  were 
sheared  under  the  action  of  the  earthquake,  leaving  the  plate  hanging 
by  the  eighth  rivet  at  the  time  I saw  it  (PI.  XL VII,  B). 

One  detail  of  the  bracing  in  the  ferry-building  tower,  of  which 
a satisfactory  photograph  could  not  be  procured,  was  as  follows: 

The  wall  girders  at  the  different  floor  levels  were  utilized  for  the 
wind  struts  of  the  bracing.  In  the  lower  part  of  the  tower  the  diag- 
onal tie-rods  were  fastened  directly  to  the  wind  struts.  The  ends 
of  the  wind  struts  rested  between  upper  and  lower  seats  attached 
to  the  columns,  and  were,  as  a rule,  bolted  to  each  of  those  seats 
with  nothing  but  two  J-inch  bolts,  the  idea  evidently  being  that,  as 
the  struts  resisted  compression  only,  it  was  not  necessary  to  fasten 
them  to  the  columns  with  anything  designed  to  resist  any  consid- 
erable force  tending  to  separate  them  from  the  column.  The  upper 
seat  was  evidently  designed  to  take  the  vertical  component  of  the 
stress  in  the  diagonal,  and  the  lower  seat  to  take  this  load  in  addi- 
tion to  the  ordinary  load  which  the  wind  strut  transmitted  to  it  in 
its  capacity  as  a girder.  The  bolts  fastening  the  ends  of  several  of 
the  wind  struts  to  their  seats  had  been  sheared,  and  the  struts  had 
almost  slipped  out  from  between  the  seats. 

fn  the  upper  part  of  the  tower  a different  method  was  adopted, 
the  diagonal  tie-rods  being  fastened  to  bent  plates  that  passed  around 
the  outside  of  the  columns  opposite  the  ends  of  the  wind  struts.  Xo 
shearing  of  the  bolts  or  slipping  of  the  struts  was  noticeable  at  these 
points.  It  is  plainly  apparent  that  ordinary  assumptions  made  in  de-  1 
signing  wind  struts  will  not  apply  when  it  is  desired  that  the  bracing 
shall  resist  earthquakes.  There  is  evidently  a tendency  for  the  col- 
umns at  the  ends  of  a wind  strut  to  buckle  outward,  and  thereby  also 
a tendency  to  pull  the  strut  out  from  between  its  seats.  In  fasten- 
ing bracing  to  resist  earthquake  shock,  therefore,  the  struts  should 
be  fastened  to  the  columns  at  their  ends  much  more  securely  than 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES.  107 

is  ordinarily  done.  In  fact,  if  the  diagonal  is  to  be  fastened  directly 
to  the  wind  strut,  there  should  be  a connection  between  the  strut  and 
the  column  capable  of  taking  up  the  horizontal  component  of  the 
stress  in  the  diagonals.  Knee  braces,  such  as  those  used  in  the  Call 
Building,  possess  a manifest  superiority  over  ordinary  bracket  seats 
in  construction  of  this  sort.  An  examination  of  the  condition  of  the 
bracing  in  the  ferry-building  tower  can  leave  no  doubt  whatever 
that  the  tower  was  just  on  the  point  of  total  collapse.  Conditions 
were  so  bad  that  the  superintendent  of  the  contracting  firm  that 
was  taking  the  masonry  down  evidently  felt  a little  uneasy  about 
what  would  happen  when  the  masonry  • covering  was  removed  from 
the  portion  of  the  steel  work  where  the  bracing  was  most  seriously 
damaged.  He  was  proceeding  with  great  judgment  and  caution, 
however,  and  no  doubt  succeeded  not  only  in  removing  the  damaged 
masonry  with  safety,  but  in  so  tying  together  the  steel  work  as  to 
avoid  all  danger  of  collapse. 

A part  of  the  masonry  in  the  east  front  of  the  tower  was  precipi- 
tated from  its  position  (Pl.  XL VI,  A)  and  fell  through  the  sky- 
light and  onto  the  floor  of  the  corridor  in  the  upper  story  of  the 
main  building.  This  floor  consisted  of  stone  concrete,  reenforced 
with  expanded  metal,  and  carried  by  steel  beams  with  spans  appar- 
ently of  7 or  8 feet.  The  contractor’s  superintendent,  already  men- 
tioned, told  me  that  he  thought  the  amount  of  masonry  so  precipi- 
tated on  this  floor  amounted  to  30  or  40  tons.  It  punched  in  the 
floor  one  small  hole  not  much  larger  than  a man’s  fist,  but  nothing  of 
any  size  got  through.  It  is  doubtful  whether  any  form  of  floor 
arch  or  slab  except  reenforced  concrete  and  possibly  solid  brick 
would  have  stood  this  test  so  successfully.  Certainly  no  hollow-tile 
floor  such  as  those  in  ordinary  use  would  have  stood  it  for  a moment ; 
the  falling  mass  would  have  gone  on  through  to  the  ground. 

Along  the  west  front  of  the  ferry  building,  about  halfway  up  the 
second-story  window  piers,  most  of  the  stonework  had  slipped  about 
an  inch.  Some  of  the  first-story  piers  were  so  badly  shattered  by  the 
earthquake  that  they  had  to  be  boxed  in  to  prevent  the  loose  stone 
from  falling.  There  were  in  the  floor  construction  of  the  tower  and 
of  the  building  proper  a few  cracks  which  I thought  might  be  due 
to  the  earthquake,  although  it  is  possible  that  they  may  have  been 
shrinkage  cracks.  I was  not  able  to  get  any  convincing  testimony 
on  this  point,  but  I have  seen  a good  many  shrinkage  cracks  and  am 
of  the  opinion  that  most  of  these  cracks  were  due  to  the  earthquake 
and  not  to  shrinkage.  On  the  whole,  the  ferry  building  stood  the 
shock  remarkably  well.  It  would  seem  to  be  the  part  of  wisdom, 
however,  to  tear  the  tower  down  altogether  and  not  to  rebuild  it. 


108 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


UNION  TRUST  COMPANY’S  BUILDING. 

The  ordinary  steel-frame  Union  Trust  Building,  with  terra-cotta 
fireproofing,  came  through  the  earthquake  in  about  the  same  condi- 
tion as  the  average  fireproof  building  in  Baltimore  after  the  fire. 
From  the  exterior  it  presented  the  appearance  of  having  stood  the 
ordeal  about  as  well  as  any  other  building  in  San  Francisco  that 
was  completely  gutted.  The  damage,  however,  was  probably  at 
least  as  great  as  that  suffered  by  such  buildings  as  the  Continental 
Trust  in  Baltimore.  Lower  webs  were  off  in  many  places,  and 
column  and  girder  coverings  were  damaged  to  a considerable  extent 
(PI.  L ,B). 

MISCELLANEOUS  STRUCTURES. 

GENERAL  DISCUSSION. 

A number  of  buildings  of  fire-resistant  construction  in  San  Fran- 
cisco, such  as  the  Mutual  Savings  Bank,  the  Hibernia  Bank  (see  PI. 
XXXVII,  A ),  and  several  others,  have  not  been  specifically  men- 
tioned in  this  report,  but  they  presented  nothing  of  more  than  ordi- 
nary interest.  Detailed  descriptions  have  been  given  of  at  least 
one  example  of  everything  that  was  typical,  and  practically  every- 
thing described  in  detail  was  typical  of  many  other  cases  of  the 
same  general  class. 

A building  at  First  and  Xatoma  streets  had  naked  cast-iron 
columns,  steel  girders,  reenforced-concrete  beams  from  girder  to 
girder,  and  reenforced-concrete  slabs  from  beam  to  beam.  The 
reenforcement  of  the  concrete  beams  consisted  of  plain  round  rods 
passing  through  the  webs  of  the  girders  and  fastened  with  nuts  in 
the  same  way  as  tie-rods.  The  aggregate  of  the  concrete,  in  the 
beams  at  least,  seems  to  have  been  of  stone.  Some  of  the  slabs  looked 
as  if  some  cinders  had  been  used  in  them,  but  this  appearance  may 
have  been  due  to  damage  by  the  fire.  At  any  rate  the  concrete  was 
very  badly  damaged,  as  will  be  seen  in  some  of  the  rear  bays  of  the 
upper  floor.  Where  the  deflection  was  worst  there  may  have  been 
something  precipitated  upon  the  floor,  but  even  at  other  points  con- 
siderable deflection  was  apparent,  together  with  serious  damage  to 
the  concrete.  It  was  evident,  from  the  beams  hanging  down  in  the 
front,  that  in  erecting  this  building  the  forms  for  the  beams  were 
filled  first  and  the  slabs  were  put  on  afterwards,  so  that  there  was 
no  adequate  bond  between  the  beams  and  the  slabs.  The  reenforce- 
ment of  the  slabs  in  this  building  was  a very  light  twisted-wire  mesh, 
and  the  only  wonder  is  that  it  held  as  well  as  it  did.  The  remains 
of  a furred  wire-lath  ceiling  were  visible,  and  the  failure  of  this 
ceiling  is  typical  of  what  occurred  in  many  other  buildings. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


109 


It  will  be  noted  that  there  was  no  reenforced-concrete  construction, 
pure  and  simple,  in  San  Francisco.  The  warehouse  of  the  Bekins 
Van  and  Storage  Company  (PI.  XXVII,  X),  in  process  of  construc- 
tion, had  reenforced-concrete  columns  and  floor  construction  and 
brick  walls.  The  walls  were  badly  damaged  by  the  earthquake,  but 
the  reenforced  concrete  was  absolutely  uninjured.  This  building, 
however,  was  unfinished,  and  the  lower  portion  of  it  was  not  sub- 
jected to  the  stresses  which  would  have  resulted  had  it  been  com- 
plete, with  all  its  contents.  In  that  case  the  energy  due  to  the 
vibration  of  the  greater  superincumbent  mass  might  have  produced 
effects  which  were  not  produced  in  its  unfinished  condition. 

One-half  of  the  circular  observatory  on  Strawberry  Hill,  in  Golden 
Gate  Park  (PI.  XXIII,  X),  was  thrown  down  by  the  earthquake. 
I did  not  make  a personal  examination  of  it,  except  from  a distance, 
but  was  informed  that  it  had  been  reenforced  with  heavy  iron  rods 
bedded  in  the  masonry.  It  was  reported  to  me  that  these  rods  were 
broken  at  the  point  where  the  collapsed  portion  had  separated  from 
the  part  still  standing.  The  general  effect  of  the  earthquake  on 
hollow  circular  structures  of  all  sorts  seems  to  have  been  a tendency 
to  increase  their  diameter.  Where  this  tendency  was  very  marked, 
it  naturally  caused  their  collapse. 

Practically  all  the  other  photographs  submitted  and  not  spe- 
cifically referred  to  in  the  foregoing  pages  were  taken  with  a view 
of  showing  earthquake  damage.  The  tower  of  the  church  next  to 
the  old  Mission  Dolores  was  dangerously  near  being  thrown  down, 
and  had  to  be  pulled  down  later,  as  shown  in  PL  XXIII,  B.  PL 
XXXVII,  B,  is  a view  of  a brewery  which  had  been  four  stories 
high,  with  a tower  at  the  corner  extending  to  a considerably  greater 
height  than  the  building.  The  damage  was  due  to  earthquake  alone. 
PL  XXI,  X,  shows  a case  of  earthquake  damage  pure  and  simple. 
It  will  be  observed  that  the  face  bricks  were  not  bonded,  and  were 
thrown  down  in  large  quantities.  None  of  the  brickwork  in  this 
building  seems  to  have  been  of  a very  good  quality. 

An  old-fashioned  brick  building  of  ordinary  construction  near 
Fort  Mason  appeared  to  have  survived  the  earthquake  absolutely 
undamaged.  This  example  indicates  the  variation  in  the  intensity 
of  the  earthquake  within  relatively  short  distances. 

PL  XXXIII,  X,  shows  a building,  known  as  the  Butler  Building, 
which  was  partially  completed  at  the  time  of  the  earthquake.  When 
I first  saw  it  the  side  wall,  which  appears  in  the  illustration  as 
nearly  torn  down,  was  standing  at  about  the  same  height  as  the  front 
wall  (shown  at  the  right  side  of  the  picture).  This  side  wall  had  a 
few  earthquake  cracks  in  it  which  were  plainly  visible,  but  it  was 
a matter  of  surprise  to  see,  a few  days  later,  that  the  wall  had  been 
practically  torn  down;  for  if  this  wall  was  damaged  sufficiently  to 


110  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

justify  its  destruction,  a great  many  walls  of  other  steel-frame  build- 
ings ought  to  have  come  down  also.  This  building  was  of  the 
ordinary  steel-frame  type,  without  any  bracing.  The  walls  were 
very  light,  and  on  the  principal  fronts  they  were  pretty  well  shaken 
to  pieces.  A superficial  examination  indicated  that  they  were  much 
more  seriously  damaged  than  the  side  wall  which  had  been  torn 
down.  This  building  appears  in  the  background  of  the  view  of  the 
Dewey  monument  (PL  XXX,  A).  At  the  time  this  view  was  taken 
a considerable  amount  of  the  masonry  in  the  front  wall  had  been 
removed,  but  there  was  still  a great  deal  which,  in  my  judgment,  was 
too  badly  damaged  to  be  safely  left. 

PL  LV  is  a panorama  taken  from  Pine  and  Powell  streets.  The 
building  on  the  left  side  of  the  street  at  the  left  is  the  Merchants’ 
Exchange.  To  the  right,  just  behind  the  high  ground  and  trees,  is 
the  Mills  Building,  and  farther  to  the  right  is  the  Union  Trust 
Building.  The  other  buildings  will  probably  be  recognized  by  per- 
sons who  are  more  or  less  familiar  with  the  city;  the  names  of  the 
chief  ones  are  given  on  the  plate.  It  will  be  observed  that  this 
panorama  covers  an  arc  of  nearly  180°.  The  Twin  Peaks  appear 
some  distance  to  the  right  of  the  city  hall. 

ORDINARY  BUILDINGS  AND  RESIDENCES. 

The  effect  of  the  earthquake  on  miscellaneous  buildings  of  the 
cheaper  class  was  more  or  less  interesting.  There  were  a number  of 
brick  dwellings  in  San  Francisco  faced  with  arch  bricks  laid  in 
Flemish  bond.  These  bricks,  of  course,  are  considerably  harder  and 
stronger  than  ordinary  red  bricks.  Though  they  make  a very  rough 
wall,  it  is  interesting  and  attractive,  like  the  old  colonial  brickwork 
in  the  East.  Apparently  these  houses  were  very  strong.  Whether 
it  was  good  luck  in  all  cases,  or  whether  this  brickwork  really  was 
much  superior  to  the  average  brickwork  used  in  San  Francisco,  I 
saw  not  a single  example  of  earthquake  damage  to  any  house  built  in 
this  way.  I noticed  eight  or  ten  of  these  dwellings,  and  not  one  of 
them  was  damaged.  The  same  fact  had  been  noticed  by  the  enlisted 
man  who  accompanied  me  as  a photographer.  He  apparently  had 
seen  a greater  number  of  buildings  of  this  kind  of  brickwork  than  I 
had,  and  he  stated  that  not  one  of  them  seemed  to  have  suffered  any 
injury,  although,  in  many  cases,  their  neighbors  had  been  seriously 
damaged. 

A considerable  number  of  frame  buildings  had  practically  col- 
lapsed under  the  earthquake ; some  of  them  were  thrown  bodily  from 
their  foundations.  Plaster  was  generally  shaken  loose  from  wooden 
lathing,  but,  so  far  as  I saw,  none  that  was  applied  to  good  metallic 
lathing,  such  as  heavy  wire  lath  or  expanded  metal,  had  been  shaken 
down. 


BEHAVIOR  OF  INDIVIDUAL  STRUCTURES. 


Ill 


As  a result  of  my  observations,  I am  inclined  to  think  that  a 
building  of  the  following  type  would  be  very  desirable  for  residential 
purposes  in  an  earthquake  country : 

The  frame  should  be  of  timber,  rather  heavy  and  thoroughly 
braced,  with  all  the  vertical  members  continuous  from  bottom  to  top, 
or  else  thoroughly  spliced.  The  horizontal  members  should  be  made 
as  nearly  continuous  as  possible — preferably  by  full  splices.  Hori- 
zontal and  vertical  members  should  also  be  fastened  together  as 
rigidly  as  possible,  diagonal  braces  being  used  wherever  conditions 
will  permit.  The  frame  should  be  covered  on  the  outside  with 
expanded  metal  and  this  metal  plastered  on  both  sides,  a good  deal 
of  cement  being  used  in  the  plaster.  The  exterior  can  be  finished  in 
stucco  or  pebble  dash,  as  desired.  The  interior  of  the  frame  should 
be  covered  with  expanded-metal  lathing  and  the  ordinary  interior 
plaster-finish  put  on.  The  ceilings  also  should  be  finished  with 
expanded  metal  and  plaster.  In  my  judgment,  a building  of  this 
sort  could  be  put  up  for  very  little  more  than  the  cost  of  an  ordinary 
frame  dwelling,  and  would  not  only  come  through  an  earthquake 
much  better,  but  would  be  very  much  more  difficult  to  set  on  fire  and 
would  burn  much  more  slowly  after  it  was  on  fire. 

CHIMNEYS. 

Chimneys  seemed  to  be  shaken  down  by  the  earthquake  every- 
where ; even  where  there  was  no  other  damage  this  result  was  almost 
universal.  The  chimneys,  as  a rule,  were  built  of  bricks  laid  in  lime 
mortar,  and  generally  broke  off  at  the  point  where  they  came  through 
the  roof.  Reenforced-concrete  chimneys  with  a terra-cotta  lining 
would  be  very  little  more  expensive  than  the  kind  that  were  ordi- 
narily used  in  San  Francisco,  and  would  have  suffered  very  much 
less  damage.  If  any  chimney  projects  a considerable  distance  above 
the  roof,  it  would  be  advisable  to  brace  it  near  its  upper  end  to  the 
roof  in  some  way,  so  that  it  would  not  be  free  to  vibrate.  It  seems 
probable  that  this  plan  might  have  saved  some  of  the  chimneys  that 
failed.  Appearances  seemed  also  to  warrant  the  conclusion  that  in 
the  vibration  some  chimneys  were  brought  up  short  against  the  roof 
framing  and  thus  caused  to  break  off  at  this  point.  If  there  had 
been  a little  more  room  for  relative  vibration  between  the  chimney 
and  the  framing,  it  seems  possible  that  some  of  these  chimneys  would 
not  have  fallen.  The  best  way  to  prevent  such  damage  is  to  build 
the  chimneys  of  reenforced  concrete  or  of  some  other  material  that 
has  both  rigidity  and  great  tensile  strength.  Such  chimneys  would 
not  ordinarily  break  off,  even  though  they  jostled  against  the  roof 
timbers. 


112 


THE  SAN  FEAN CISCO  EAKTH QUAKE  AND  FIKE. 


BRICK  SMOKESTACKS. 

There  were  a great  many  brick  smokestacks  in  San  Francisco, 
nearly  all  of  which  suffered  more  or  less  damage.  For  some  reason 
circular  stacks  seemed  to  suffer  more  than  square  ones,  but  the  num- 
ber of  square  stacks  in  evidence  was  not  sufficient  to  justify  general 
conclusions. 

The  views  of  brick  stacks  speak  for  themselves  to  a great  extent. 
The  stack  of  the  Valencia  street  power  station  (PI.  LIII,  A)  was  of 
some  interest  because  of  its  peculiar  cross  section — an  eight-pointed 
star.  At  the  vertices  of  two  diametrically  opposite  reentrant  angles 
the  stack  was  split  practically  from  top  to  bottom.  The  ruins  of  a 
circular  stack,  situated  near  San  Jose,  are  shown  in  PL  XIII,  A. 

CONDITIONS  OUTSIDE  OF  SAN  FRANCISCO. 

OAKLAND. 

I made  one  trip  to  Oakland  and  went  through  the  greater  part  of 
the  town.  A good  many  chimneys  had  been  shaken  down  and  the 
front  walls  of  a number  of  ordinary  brick  buildings  had  been  pre- 
cipitated into  the  street.  Several  steel-frame  buildings  faced  with 
sandstone  were  badly  racked,  and  in  places  some  of  the  stone  had 
been  shaken  into  the  street.  Some  of  the  steel- frame  buildings 
showed  the  same  kind  of  damage  as  the  Monadnock  and  new  Chroni- 
cle buildings  in  San  Francisco.  The  damage  in  Oakland  in  general 
was  not  different  in  type  from  that  in  San  Francisco,  but  it  was 
much  less  extensive,  and  individual  cases  were,  as  a rule,  much  less 
marked. 

PALO  ALTO. 

I visited  Palo  Alto,  and  through  the  courtesy  of  President  Jordan, 
of  the  Leland  Stanford  Junior  University,  was  enabled  to  make  a 
satisfactory  examination  of  the  damaged  buildings  at  the  university. 
These  buildings  represented  in  a general  way  three  different  types. 
Among  them  were  some  old  buildings  faced  with  yellow  sandstone, 
which  had  been  built  in  the  early  days  by  hired  labor,  under  the 
supervision  of  Governor  Stanford  himself.  All  the  sandstone  used 
at  the  university  was  of  a light  yellow-buff  color,  rather  soft,  and 
apparently  not  very  strong.  In  these  older  buildings,  however,  the 
cut  stone  had  good  wide  beds,  was  carefully  laid,  was  well  bonded  to 
the  backing,  and  was  solidly  backed  up  with  brickwork.  These 
buildings  were  damaged  seriously,  but  by  no  means  beyond  repair. 

In  addition  to  these  older  buildings  there  were  some  newer  ones  of 
the  same  general  design,  but  the  sandstone  facing  was  thinner  and 
the  beds  not  so  well  cut  nor  so  wide.  The  backing  was  not  so  good. 


CONDITIONS  OUTSIDE  OF  SAN  FKANCISCO.  113 

Much  of  it  consisted  of  rubble  made  of  very  small  pieces  of  stone, 
apparently  gathered  up  where  stonecutters  had  been  working. 
Many  of  these  spalls  were  not  larger  than  a man’s  fist,  and  in  places 
4 or  5 square  feet  of  the  wall  was  entirely  backed  up  with  this  mate- 
rial. The  bonding  of  the  stone  facing  to  the  backing  seemed  to  be 
less  thorough  in  the  new  buildings  than  in  the  old.  In  short,  the 
newer  buildings  conformed  rather  to  the  modern  commercial  stand- 
ard of  building  construction;  the  old  ones  approached  the  monu- 
mental. The  newer  buildings  suffered  materially  more  than  the  old. 
They  were  not,  however,  of  a type  that  would  indicate  culpable  negli- 
gence or  incapacity  on  the  part  of  anyone  connected  with  their  design 
and  erection,  although  they  were  distinctly  inferior  in  type  to  the 
older  buildings.  The  mortar  used  was  not  by  any  means  poor.  It 
seems  to  have  been  lime  mortar  gaged  with  cement.  I tried  it  at  a 
number  of  points  where  the  buildings  had  suffered  very  severely,  and 
it  was  distinctly  better  than  the  average  mortar  found  in  ordinary 
commercial  work,  although  not  as  good  as  straight  cement  mortar 
would  have  been. 

The  buildings  of  the  third  class  at  Stanford  University  were  built 
of  concrete.  The  girls’  dormitory  had  concrete  walls  and  timber 
interior  construction,  and  in  the  central  portion  of  the  Leland  Stan- 
ford Junior  Museum,  the  oldest  part  of  the  building,  the  walls  and 
interior  construction  were  of  reenforced  concrete.  There  were  two 
wings,  built  of  brickwork,  with  reenforced-concrete  floor  construc- 
tion. It  is  reasonable  to  suppose  that  the  intensity  of  the  force  ap- 
plied to  this  building  by  the  earthquake  was  nearly  uniform  over  the 
entire  structure.  The  two  brick  wings  were  practically  shaken 
down,  suffering,  I should  judge,  considerably  more  than  50  per  cent 
damage.  The  reenforced-concrete  central  portion,  viewed  from  the 
exterior,  seemed  absolutely  undamaged.  In  the  interior  a few  cracks 
had  opened  up,  but  they  were  not  of  serious  consequence.  I should 
judge  that  a thousand  dollars  would  easily  cover  all  the  repairs  to  this 
part  of  the  building.  Its  valuable  contents  were,  to  a large  extent, 
thrown  to  the  floors  and  smashed,  involving  a considerable  loss;  but 
the  structure  itself  suffered  almost  no  injury.  The  only  damage  to 
the  girls’  dormitory  was  caused  by  a chimney  that  toppled  over  and 
crashed  down  through  the  roof,  doing  some  damage  on  the  inside. 
By  good  luck,  no  one  was  hurt  in  this  building.  The  concrete  wall 
showed  one  or  two  cracks,  which,  however,  were  said  to  be  shrinkage 
cracks  that  had  appeared  soon  after  the  building  was  finished.  The 
earthquake  apparently  had  caused  no  visible  damage  of  any  sort  in 
the  exterior  walls. 

It  was  noticed  that  those  buildings  which  had  completely  trussed 
roofs  suffered  much  less  than  those  in  Avhich  the  walls  had  to  take 


114 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


the  thrust  of  the  rafters.  This  result  was  naturally  to  be  expected, 
and  indicates  that  in  earthquake  countries  walls  should  not  be  sub- 
jected to  the  thrust  of  the  rafters  at  all.  The  damage  at  the  univer- 
sity also  indicated  clearly  the  necessity  of  thoroughly  tying  all  the 
walls  to  the  roof  construction,  gable  walls  as  well  as  others.  The 
university  post-office  building  was  said  to  be  of  reenforced  concrete 
and  undamaged.  Very  good  illustrations  of  the  damage  at  Stanford 
University  can  be  seen  in  the  Engineering  News  for  May  10,  1906, 
and  in  the  Engineering  Record  for  May  12,  1906.  (See  also  Pis. 
XIV,  A;  XV;  XVI;  XVII,  B;  XVIII.)  A concrete-block  building 
in  the  town  of  Palo  Alto  was  totally  demolished. 

OTHER  TOWNS. 

Concrete-block  buildings  elsewhere  were  also  reported  as  totally 
destroyed.  The  various  structures  of  the  Southern  Pacific  Railroad 
along  the  coast  division  had  suffered  more  or  less  damage.  One  or 
two  stations  faced  with  a sandstone  similar  to  that  used  at  the  Le- 
land  Stanford  Junior  University,  and  built  in  the  ordinary  style, 
had  been  very  seriously  damaged.  One  station,  which  seemed  to 
have  been  built  a little  more  carefully  and  with  larger  stones  than  the 
rest,  was  in  very  much  better  condition  than  most  of  them.  The  city 
hall  at  Redwood  had  a central  circular  tower,  with  a dome  supported 
on  steel  work,  much  as  in  the  city  hall  at  San  Francisco  (PI. 
XXXI),  though  on  a smaller  scale,  and  suffered  almost  exactly  the 
same  kind  and  degree  of  damage. 

FORTIFICATIONS. 

I visited  the  old  brick  fort  at  the  Presidio  and  also  most  of  the 
batteries  along  the  face  of  the  cliff.  There  were  a few  cracks  in  the 
old  brick  fort,  but  nothing  to  indicate  that  they  might  not  have 
been  due  to  settling  as  well  as  to  earthquake.  An  inspection  of  the 
new  emplacements  from  the  exterior  showed  no  visible  signs  of 
damage  whatever.  As  reports  on  these  matters  are  made  by  officers 
especially  in  charge  of  the  work,  I did  not  attempt  to  make  a detailed 
inspection  of  the  fortifications. 

RESERVOIRS,  PIPE  LINES,  AND  OTHER  STRUCTURES  ALONG  THE  FAULT  LINE. 

The  following  details  were  derived  from  a perusal  of  the  report  by 
Professors  Marx  and  Wing,  already  mentioned  (p.  63)  . 

The  Spring  Valley  Water  Company  had  among  its  reservoirs  two 
known  as  Crystal  Springs  Lake  and  San  Andreas  Lake.  The  line 
of  the  fault  that  caused  the  earthquake  is  said  to  run  directly  through 
both  of  these  reservoirs.  Crystal  Springs  Lake  has  a large  and  high 
concrete  dam;  it  is  also  subdivided  by  an  old  earth  dam  that  was 


CONDITIONS  OUTSIDE  OF  SAN  FRANCISCO. 


115 


formerly  the  main  dam,  when  the  reservoir  was  smaller  than  it  is 
now.  The  concrete  dam,  which  was  parallel  to  the  fault  and  of 
course  very  near  to  it,  was  absolutely  uninjured  (PL  XI,  B)  ; the 
earth  dam,  which  lay  across  the  fault  approximately  at  right  angles, 
showed  definite  signs  of  disturbance  and  lateral  displacement.  Longi- 
tudinal and  transverse  cracks  appeared  on  top  of  the  earth  dam,  and 
some  of  the  former  were  reported  to  have  extended  to  a depth  of  at 
least  3 or  4 feet.  The  transverse  cracks  were  said  to  be  less  well 
defined  and  to  indicate  rather  a general  disturbance  on  each  side  of 
the  fault  line,  about  one-fourth  of  a mile  away,  and  was  absolutely 
to  which  it  was  damaged  could  not  be  ascertained. 

San  Andreas  Lake  is  retained  by  a high  earth  dam.  The  fault  ran 
under  the  east  end  of  this  dam  and  produced  considerable  disturb- 
ance over  a strip  about  150  feet  wide,  though  the  dam  was  not  seri- 
ously injured.  A concrete  culvert  inlet  was  connected  with  this  dam, 
and  one  of  the  worst  transverse  cracks  noted  ran  diagonally  over  the 
culvert,  but  the  culvert  itself  was  uninjured.  Besides  the  high  con- 
crete dam  of  Crystal  Springs  Lake,  the  water  company  had  another 
smaller  concrete  dam  at  Searsville.  This  dam  also  was  parallel  to 
the  fault  line,  about  one-fourth  of  a mile  away,  and  was  absolutely 
uninjured. 

The  Spring  Valley  Water  Company  had  three  main  conduits  run- 
ning into  San  Francisco.  One  of  these,  known  as  the  Pilarcitos 
conduit,  consisted  largely  of  22-inch  and  30-inch  riveted  pipe  and 
24-inch  cast-iron  pipe;  some  feeders  were  built  of  wooden  flume. 
The  conduit  crossed  and  recrossed  the  line  of  the  fault,  and  was  so 
badly  wrecked  that  the  company  has  decided  to  abandon  it — no 
doubt  a wise  decision,  because  the  location  along  the  line  of  the  fault 
was  a very  bad  one.  Wherever  the  conduit  crossed  the  fault  line  it 
was  destroyed.  In  some  places  there  was  a longitudinal  displacement 
of  as  much  as  84  inches,  which  either  telescoped  the  pipe  or  pulled 
it  apart,  as  the  case  might  be.  (VieAvs  of  these  effects  are  given  in 
PI.  IX.)  It  made  no  difference  whether  the  conduit  was  in  firm 
ground,  or  in  soft  ground,  or  carried  on  a trestle  over  marshy  ground; 
the  result  was  the  same  wherever  it  crossed  the  fault.  In  many 
places  where  the  conduit  was  carried  on  trestlework  the  timber 
showed  considerable  decay.  Whether  sound  timber  structures  would 
have  withstood  the  shock  seems  open  to  question.  (See  also  PL 

x,  A.)  ^ 

Within  the  city  proper  the  reservoir  known  as  Lake  Honda  was 
damaged  by  the  cracking  of  its  concrete  lining.  It  is  reported  that 
this  cracking  was  due  to  the  displacement  of  a retaining  wall  by  a 
sliding  bank  set  in  motion  by  the  earthquake. 

The  distributing  mains  of  the  Spring  Valley  Water  Company, 
wherever  they  passed  through  soft  or  made  ground,  suffered  in  the 


116  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

same  way  as  the  conduits  and  pipes  which  crossed  the  fault  line. 
(See  the  maps,  Pis.  LVI  and  LYII.)  Some  subaqueous  pipe  lines 
crossing  the  bay  seem  not  to  have  been  injured. 

Two  interesting  earth  dams  are  those  at  the  San  Jose  Water  Com- 
pany’s Saratoga  reservoir,  which  lies  in  a saddle  in  the  mountains 
and  is  retained  by  an  earth  dam  at  either  end.  The  fault  runs 
directly  through  the  reservoir,  crossing  both  dams  approximately 
at  right  angles.  It  was  reported  that  near  the  east  end  of  the  north 
dam  transverse  cracks  were  formed,  which  extended  through  the 
body  of  the  dam.  There  was  also  a longitudinal  crack  on  top  and 
some  settling  of  the  upstream  half  of  the  dam.  The  reservoir  seems 
to  have  been  full  at  the  time  of  the  earthquake,  but  no  evidence  was 
found  that  any  water  had  escaped  through  this  dam.  At  the  south 
end  of  the  reservoir  the  fault  line  intersected  not  only  the  dam  but 
the  10-inch  outlet  pipe,  which  was  broken  by  the  earthquake.  Con- 
siderable damage  seems  to  have  been  done  to  the  dam  by  the  water 
escaping  through  this  broken  outlet  pipe.  Whether  the  dam  itself 
would  have  been  seriously  injured  by  the  earthquake  but  for  this 
pipe  can  not  probably  be  determined. 

Professors  Marx  and  Wing  also  noted  in  the  vicinity  of  the  fault 
a number  of  monolithic  concrete  bridges,  all  of  which  were  unin- 
jured; none  of  them,  however,  absolutely  crossed  the  fault  line. 
(Cf.  PI.  XI,  A.)  These  observers  also  report  that  a small  concrete 
reservoir,  built  partly  in  embankment  and  partly  in  excavation,  was 
wrecked  by  the  earthquake,  and  seem  to  think  that  such  structures 
would  better  be  built  in  excavation.  They  found  that  some  high 
timber  frames  carrying  water  tanks,  as  well  as  similar  structures  sup- 
porting steel  standpipes,  were  intact.  A steel  water  tower  at  Santa 
Clara  was  wrecked.  The  engineer  who  designed  this  tower  gives  an 
explanation  of  its  failure,  however,  in  the  Engineering  News  for 
May  10,  1906.  Very  probably  his  explanation  is  correct,  and  if  so, 
there  is  no  reason  why  steel  towers  should  not  be  used.  Doctor 
Jordan  told  me  of  one  tower  that  he  saw  which  had  collapsed  as  a 
result  of  the  earthquake,  and  in  which  the  nuts  on  the  upper  ends  of 
the  anchor  rods  stripped  the  threads  so  as  to  allow  the  tower  as  a 
whole  to  be  thrown  over. 

GENERAL  CONCLUSIONS. 

THE  REBUILDING  OF  SAN  FRANCISCO. 

Unless  future  earthquakes  are  very  much  more  severe  than  any  that 
have  occurred,  there  is  no  reason  why  the  rebuilding  of  San  Francisco 
should  not  be  a successful  commercial  enterprise.  It  seems  highly 
improbable  that  there  will  ever  be  earthquakes  more  severe  than 
that  of  April  18,  1906.  There  is  no  doubt  that  the  city  can  be  rebuilt 


DISTRIBUTION  SYSTEMS  FOR  WATERWORKS. 


117 


so  that,  although  it  will  suffer  damage  from  future  earthquakes, 
this  damage  will  not  be  at  all  fatal,  and  the  city  will  not  burn  up  as 
a result  of  it. 

DISTRIBUTION  SYSTEMS  FOR  WATERWORKS. 

In  a city  subjected  to  earthquakes  it  seems  practically  impossible 
to  suggest  any  method  of  construction  which  will  make  the  mains 
and  distributing  pipes  at  all  times  perfectly  secure.  In  my  judgment 
the  only  remedy  is  to  have  within  the  city  itself  a large  storage 
capacity,  distributed  among  various  reservoirs,  and  to  have  a more 
than  ordinarily  complete  gridiron  oi  mains  with  gate  valves  to  cut 
out  any  main  at  every  intersection.  Further,  the  mains  should  be 
larger  than  would  ordinarily  be  required,  so  that  if  a portion  of  the 
gridiron  were  shattered  it  could  be  cut  out,  but  the  water  could  be 
brought  in  undiminished  quantities  to  the  perimeter  of  the  shat- 
tered area  from  all  undamaged  parts  of  the  gridiron;  that  is,  the 
mains  should  be  so  large  that,  although  the  water  would  have  farther 
to  travel  in  this  case,  there  would  be  an  adequate  supply  for  fighting 
fire,  if  necessary,  in  the  area  where  the  mains  were  shattered. 

It  would  seem  that  in  a city  like  San  Francisco  a special  system 
of  high-pressure  salt-water  mains,  supplied  from  a pumping  station, 
would  be  the  best  solution  of  the  fire-fighting  problem  so  far  as  the 
congested  district  is  concerned.  This  plan  has  been  recommended  by 
the  National  Board  of  Fire  Underwriters,  and  it  is  probably  the 
wisest  one  under  the  circumstances.  The  pumping  statiorr  should, 
of  course,  be  protected  from  earthquake  damage  in  every  possible 
way.  Perhaps  it  should  be  a floating  station.  The  salt-water  mains 
should  be  so  laid  out  and  so  interconnected  that  nothing  short  of  gen- 
eral destruction  of  the  entire  system  could  wholly  shut  off  the  water 
from  any  considerable  area. 

In  a city  like  San  Francisco,  where  there  is  practically  no  damage 
from  freezing,  it  would  seem  worth  while  to  run  the  mains  exposed 
everywhere,  so  that  breaks  could  be  located  almost  immediately.  As 
these  breaks  would  ordinarily  occur  only  in  scattered  localities,  and 
would  not  be  very  great  in  extent  themselves,  it  ought  to  be  possible 
to  repair  them  in  time  to  prevent  any  general  destruction  of  the  city 
by  fire.  Running  the  mains  exposed  would,  of  course,  introduce  diffi- 
cult problems,  at  street  crossings,  but  there  is  little  doubt  that  such 
problems  could  be  solved  successfully  if  they  were  seriously  studied. 
All  this  means  greatly  increased  expense  in  the  distribution  sys- 
tem, but  in  a situation  such  as  that  of  San  Francisco  it  seems  to  be 
required. 

The  earthquake  effects  at  San  Francisco  also  indicate  clearly  that 
a special  study  should  be  made  of  the  problem  of  promptness  in 
emergency  repairs  to  the  conduits  and  mains.  It  seems  certain  that, 
7171— Bull.  324—07—9 


118 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


in  the  immediate  vicinity  of  existing  faults  and  near  areas  including 
any  considerable  amount  of  made  ground,  both  conduits  and  mains 
may  be  expected  to  suffer  serious  damage.  At  one  point  on  Van 
Aess  avenue  (see  B,  PI.  LVI),  where  I happened  to  see  the  mains 
uncovered,  a heavy  water  pipe,  apparently  about  20  inches  in  diame- 
ter, had  been  broken  into  pieces  not  more  than  2 feet  long.  The  total 
length  of  the  break,  however,  was  not  more  than  40  or  50  feet,  so  far 
as  I could  judge  from  what  I saw  uncovered.  It  would  seem  that  this 
main  might  have  been  spliced  in  a few  hours  had  there  been  some 
means  of  rapidly  plugging  the  broken  ends  on  either  side  of  the 
break  and  making  a number  of  taps  in  the  undamaged  parts  with 
parallel  lengths  of  fire  hose  of  large  size.  With  gate  valves  at  short 
intervals  it  ought  to  be  possible  to  cut  out  any  damaged  portion  of 
the  system  by  connecting  through  with  fire  hose  in  such  a way  as  to 
maintain  at  least  a partial  supply  of  water  for  fire-fighting  purposes. 
Some  similar  plan  on  a larger  scale  might  be  devised  for  repairing 
conduits. 

It  would  also  seem  desirable,  wherever  an  important  conduit  or 
main  crosses  filled  ground  or  material  soft  enough  to  suffer  con- 
solidation as  a result  of  thorough  shaking,  to  carry  the  main  on  piles 
or  other  foundations  reaching  to  firm  material  below.  Wherever 
there  was  filled  ground  the  vibration  due  to  the  earthquake  seemed 
to  have  much  the  same  effect  as  would  be  produced  in  a vessel  that 
had  been  loosely  filled  with  sand  and  then  subjected  to  vibration;  as 
is  well  known,  the  sand,  under  such  circumstances,  will  suffer  con- 
solidation to  a very  appreciable  extent,  which  naturally  lowers  its 
surface  by  an  amount  corresponding  in  a general  way  to  the  intensity 
of  the  vibration.  Where  a large  area  and  volume  of  made  ground  is 
subjected  to  similar  vibration,  subsidence  occurs,  and  not  only  are 
buildings  on  the  surface  thrown  down  and  destroyed,  but  water 
mains,  sewers,  etc.,  running  through  the  filled  material  are  subjected 
to  a deflection  which  necessarily  shatters  them. 

SEWERS. 

The  effect  of  the  earthquake  on  sewers  seemed  to  be  practically 
the  same  as  on  conduits  and  water  mains,  except  as  varied  by  differ- 
ence of  material,  where  such  difference  existed.  The  necessity  for 
firm  foundations  for  sewers  running  through  made  ground  is  clearly 
indicated.  The  need  of  rapid  repairs  to  the  sewers  is  not  quite  so 
great  as  in  the  case  of  the  fire  mains,  because  a city  can  get  along 
with  inadequate  sewerage  facilities,  if  necessary.  It  would  seem 
desirable,  however,  that  all  important  sewers  passing  through  made 
ground  should  be  constructed  of  the  heaviest  iron  or  steel  pipes,  and 
be  provided  with  an  adequate  foundation.  Of  course,  sewers  are  not 


FIREPROOFING  IN  CONGESTED  DISTRICTS. 


119 


under  pressure,  and  therefore  can  not  be  repaired  with  fire  hose,  as 
suggested  for  water  mains.  There  seemed  to  be  some  fear  in  San 
Francisco  that  the  breaking  of  the  sewers  and  the  water  mains  would 
cause  the  water  to  be  contaminated  by  the  sewage;  but  evidently  if 
means  were  devised  to  maintain  a good  pressure  in  the  water  pipes 
this  pressure  in  itself  would  protect  a leaky  main  from  such  con- 
tamination. 

FIRE-RESISTING  FEATURES  OF  BUILDINGS  IN  “CONGESTED 

DISTRICTS.” 

FIREPROOFING. 

The  Baltimore  and  San  Francisco  fires,  as  well  as  many  other 
fires  and  fire  tests,  have  proved  conclusively  that  commercial  meth- 
ods of  fireproofing  are  inadequate  to  stand  any  severe  test.  In  most 
buildings  the  steel  work  is  fairly ‘well  protected,  but  the  number  of 
failures  is  sufficiently  great  to  show  that  the  factor  of  safety  against 
fire  is  not  by  any  means  what  it  should  be. 

For  the  protective  covering  itself  to  suffer  complete  destruction^ 
or  almost  complete  destruction,  in  any  one  fire  is  in  itself  a failure, 
because  under  such  circumstances  the  steel  work  is  very  near  destruc- 
tion and  the  margin  of  safety  is  altogether  too  small.  It  is  more 
than  probable — almost  certain,  in  fact- — that  a detailed  investigation 
of  all  the  buildings  in  San  Francisco  would  reveal  many  “ protected  ” 
columns,  not  indicated  in  this  report,  that  buckled  as  a result  of  the 
failure  of  the  covering.  In  my  judgment,  columns  should  either  be 
covered  with  4 inches  of  brickwork,  laid  in  Portland-cement  mortar, 
and  have  all  of  the  interior  space  filled  with  concrete,  or  else  they 
should  be  inclosed  in  an  expanded-metal  jacket  and  the  entire  inte- 
rior filled  with  concrete,  so  that  the  minimum  thickness  of  the  con- 
crete would  not  be  less  than  4 inches.  Exposed  flanges  of  girders  and 
beams  should  be  protected  by  the  equivalent  of  1J  to  2J  inches  of 
solid  porous  terra  cotta,  according  to  circumstances.  If  concrete  is 
to  be  used,  this  thickness  should  be  increased  by  about  half  an  inch. 
The  protection  for  lower  flanges  should  always  be  inclosed  in  a basket 
of  expanded  metal  or  heavy  wire  lath,  securely  anchored  into  the 
side  protection  of  the  webs.  The  San  Francisco  experience  showed 
that,  even  in  a hot  fire,  such  metal-mesh  basket  work  will  largely 
retain  its  tensile  strength,  and  thus  hold  in  position  the  fireproof  cov- 
ering inside  even  though  the  latter  should  be  shattered  by  expansion 
stresses  or  otherwise.  The  webs  of  the  girders  should  be  covered  by 
4 inches  of  brickwork  or  concrete,  built  up  on  the  lower  flanges. 
Girders  should  be  completely  covered  from  bottom  to  top  before  the 
floor  systems  are  put  in,  so  that  the  collapse  of  the  latter  will  not 
expose  the  girder.  Floor  beams  should  have  heavy,  solid  protecting 


120 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


skew  backs,  not  less  than  1J  inches  thick,  or  be  covered  with  at  least 
2 inches  of  concrete.  In  an  important  work  the  protection  of  the 
lower  flanges  of  the  floor  beams  should  also  be  incased  in  expanded 
metal  or  wire  lath.  The  furred  ceilings  so  much  used  in  San  Fran- 
cisco are  a valuable  addition  to  the  fire-resisting  qualities  of  floor 
construction,  and  if  the  furring  rods  were  more  firmly  secured  the 
total  loss  here,  as  a rule,  would  be  measured  by  the  value  of  the 
plaster  alone. 

Hollow-tile  partitions  should  not  be  less  than  6 inches  thick.  The 
tiles  should  have  webs  at  least  1 inch  thick,  and  all  interior  angles 
should  be  well  filleted.  The  tiles  themselves  should  be  carefully  laid 
in  Portland-cement  mortar,  with  all  joints  absolutely  filled.  Timber 
studs  running  to  the  top  of  the  partition,  to  frame  a door  or  window 
opening,  should  be  absolutely  prohibited.  The  webs  of  floor  tiles 
should  not  be  less  than  an  inch  thick,  and  their  interior  angles  also 
should  be  well  filleted. 

The  results  at  Baltimore  and  San  Francisco  did  not,  by  any  means, 
indicate  that  either  hollow  tile  or  concrete  is  altogether  a failure  or 
altogether  a success.  Both  fires  indicated  very  clearly  that  com- 
mercial methods  of  applying  both  materials  are  inadequate,  but  also 
that  successful  results  can  be  attained  with  both  materials. 

A conflagration  never  yields  reliable  comparative  results,  but 
judging  from  such  comparative  results  as  are  available,  I think  that 
there  is  no  question  that  the  best  fire-resisting  material  available  at 
the  present  time  is  the  right  kind  of  burned  clay — that  is,  a good, 
tough,  refractory  clay,  almost  as  refractory  as  fire  clay,  made  into 
proper  shapes  and  properly  burned.  Some  commercial  hollow-tile 
work  is  made  of  good  material,  but,  as  a rule,  that  is  the  only  good 
thing  that  can  be  said  about  it.  There  can  be  no  question  that  good 
clinker  concrete,  made  of  well-burned  clinker,  Portland  cement,  and 
sand,  is  a very  efficient  fire-resisting  material.  It  is  better  than  any- 
thing except  the  better  types  of  burned-clay  products ; but  the  cinder 
concrete  commercially  applied  is,  on  the  whole,  no  better  than  the 
flimsy  hollow-tile  work  with  which  it  competes;  in  fact,  it  is  not  cer- 
tain that  it  may  not  be  worse.  The  only  way  to  determine  this  point 
would  be  to  go  through  all  the  floor  construction  in  a place  like  San 
Francisco  and  make  tests  of  the  load-carrying  capacity,  etc.,  after  a 
fire.  It  is  very  doubtful,  of  course,  whether  such  tests  will  be  made. 

If  a hollow-tile  floor,  for  instance,  loses  its  lower  webs,  the  damage 
is  very  apparent,  yet  most  of  such  floors  remain  true  and  capable  of 
carrying  considerable  loads.  A cinder-concrete  floor  which  is  even 
more  seriously  damaged  is  very  likely  to  remain  true,  for  the  reason 
that  the  fire  which  damaged  it  also  removed  its  superimposed  load 
before  the  damage  was  fully  accomplished.  A hollow  tile  which 
comes  through  a fire  without  losing  any  of  its  webs  is  as  good  as  it 


FIREPROOFING  IN  CONGESTED  DISTRICTS.  121 

was  before ; whereas  concrete  of  any  kind  which  has  come  through  a 
fire  in  which  the  temperature  has  exceeded  700°  or  800°  F.  is  inevi- 
tably damaged  in  all  cases,  owing  to  the  dehydration  of  the  cement, 
although  it  may  appear  uninjured  to  the  casual  observer.  This  prop- 
erty of  concrete,  of  maintaining  a good  face  in  spite  of  real  and  seri- 
ous damage,  is  likely  to  lead  the  layman  into  dangerous  conclusions, 
and  consequently  into  equally  dangerous  practice.  It  would  seem 
that  wherever  reenforced-concrete  floor  construction  is  used  a furred 
veiling  below  it  should  be  absolutely  required. 

The  furred  ceilings  ordinarily  used  are  too  light ; the  furring  rods 
are  not  quite  heavy  enough  and  they  are  not  adequately  secured 
to  the  floor  construction  above.  If  they  were  made  a little  heavier, 
and  were  more  firmly  secured,  it  is  probable  that,  as  a rule,  no  loss 
would  occur  except  that  of  the  plaster.  Even  if  the  furred  ceiling 
comes  down  bodily,  this  failure  is  not  apt  to  occur  until  so  late  a 
stage  in  the  fire  that  the  floor  construction  above  will  be  practically 
undamaged,  because  there  will  not  be  enough  left  of  the  fire  to  raise 
the  temperature  of  the  concrete  to  the  point  where  dehydration  of 
the  cement  will  begin.  The  presence  of  a furred  ceiling,  however,  no 
matter  how  good,  should  never  be  accepted  as  an  excuse  for  omitting 
the  protection  of  the  lower  flanges  of  the  floor  beams  and  girders.  A 
hollow-tile  floor  that  would  be  fully  equivalent  to  a reenforced-con- 
crete floor,  with  a furred  ceiling,  could  be  made  by  using  tiles  in 
which  the  minimum  thickness  of  the  webs  is  1 inch,  and  of  which  the 
material  itself  is  tough,  refractory  clay,  made  porous  by  The  addi- 
tion of  sawdust;  such  tiles  should,  however,  be  burned  to  a point 
where  the  clay  itself  is  just  short  of  vitrification.  All  the  interior 
angles,  where  the  webs  of  the  tiles  join  each  other,  should  be  rounded 
to  a radius  of  at  least  1 inch  or  1^  inches.  If  necessary  to  secure 
proper  burning,  a small  hole  three-eighths  to  five-eighths  of  an  inch 
in  diameter  might  be  allowed  through  the  mass  of  clay  at  the  inter- 
section of  the  webs. 

Tests  recently  made  of  a pattern  of  tile  used  at  the  War  College 
indicate  that  floor  tiles  subjected  to  a fire  test  will  stand  better  if 
there  is  but  one  interior  hole  through  the  tiles,  all  the  material  which 
would  otherwise  be  used  in  the  interior  webs  being  concentrated  in 
the  outer  webs,  and  the  opening  in  the  tile  being  of  circular  or  ellip- 
tical shape,  depending  on  the  height  and  width  of  the  tile.  For 
floor  arches  between  steel  beams  such  a tile  as  this  one  would  have 
to  be  used  on  the  end-construction  plan.  A specially  heavy  skew 
back  should  be  designed  to  go  with  it,  or  else  the  end  tiles  should  be 
cut  to  fit  the  profiles  of  the  beam.  The  tiles  themselves  being  so 
heavy,  the  latter  method  of  obtaining  a skew  back  would  probably 
make  the  arch  more  than  strong  enough  to  carry  its  load,  and  where 
carefully  done  might  afford  adequate  fire  protection  to  the  beams, 


122  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

although  for  that  purpose  a specially  designed  extra  heavy  side- 
construction  skew  back  would  be  better,  and  should  on  the  whole  be 
recommended  even  in  connection  with  the  heavy  end-construction 
arches  described.  It  is  probable  that  either  a good  concrete  floor 
with  the  right  kind  of  ceiling  below  it,  or  a heavy  tile  floor  such  as 
that  herein  described,  would  come  through  almost  any  fire  with  no 
damage  except  the  loss  of  the  ceiling  plaster.  These  tAvo  types  may 
therefore  be  taken  as  equivalent  in  efficiency;  they  will  probably  be 
about  equal,  also,  in  first  cost. 

It  should  be  added  that  attic  floors  and  roofs  should  be  as  carefully 
designed  to  resist  fire  as  any  other  part  of  a building.  This  is  a 
thing  that  has  rarely  been  done,  and  the  experience  of  both  Baltimore 
and  San  Francisco  shows  that  it  is  absolutely  necessary. 

PROTECTION  OF  OPENINGS. 

While  there  is  no  doubt  that  commercial  standards  of  fireproofing 
are  dangerously  inadequate,  the  greatest  trouble  of  all  is  the  fact 
that  so  little  attention  is  paid  to  protecting  the  exterior  openings  in 
a building.  Even  a very  inefficient  type  of  fire  shutter  would  prob- 
ably have  saved  some  of  the  buildings  in  San  Francisco,  which  were, 
as  a matter  of  fact,  burned  out.  A light  metal  shutter  combined 
with  a window  sprinkler  would  probably  resist  a rather  fierce  fire  for 
a long  time.  Although  the  failure  of  the  water  supply  in  San  Fran- 
cisco might  be  urged  as  one  reason  why  a window  sprinkler  would 
have  been  of  no  avail,  it  is  a fact  that  water  can  be  obtained  by  driv- 
ing wells  into  the  sand  which  underlies  the  business  portion  of  San 
Francisco  almost  everywhere.  Under  these  circumstances,  if  the  fire- 
proof buildings  had  been  fitted  with  metal  shutters,  even  no  better 
than  those  in  the  windows  of  the  hall  of  records,  and  if  each  window 
had  been  provided  with  a sprinkler  and  the  building  itself  with  its 
own  well  and  fire  pump,  it  is  probable  that  the  fire  could  have  been 
kept  out  of  a large  number  of  the  buildings.  The  protection  of 
external  openings  is  by  all  odds  the  most  important  constructive 
problem  involved  in  the  efforts  to  make  cities  proof  against  con- 
flagration, and  it  seems  probable  that  at  the  present  time  adequate 
protection  of  windows  and  doors  is  available  at  a reasonable  cost. 
In  my  judgment,  windows  protected  in  the  following  way,  even 
without  sprinklers,  might  keep  out  the  fire,  though  the  buildings 
were  shut  up  and  abandoned. 

1.  The  outer  opening  should  be  protected  with  some  form  of 
rolling  steel  shutter  or,  preferably,  with  a shutter  composed  of  sheets 
of  steel  sliding  in  very  deep  rebates  in  the  walls.  The  sheets  of  steel 
should  be  anchored  in  these  rebates  bv  means  of  angle  irons  or  rivets 
driven  so  as  to  interlock  with  a bead  to  be  placed  in  position  after 


PROTECTION  OF  OPENINGS  IN  CONGESTED  DISTRICTS.  123 


the  sheet  of  steel  is  itself  in  position.  By  providing  a pocket  in  the 
masonry  just  above  the  window  head  and  making  these  shutters  in 
three  or  four  parts,  overlapping  and  interlocking  at  the  overlap,  the 
whole  shutter  could  be  slid  up  into  the  wall  practically  out  of  sight. 
This  arrangement  would  necessitate  window  openings  slightly  lower 
than  those  used  in  many  commercial  buildings,  but  the  loss  of  light 
would  not  be  very  serious.  The  metal  shutters  when  closed  should 
overlap  the  window  opening  in  all  directions  by  at  least  6 inches. 
This  overlapping  could  be  accomplished  at  the  sill  without  making  a 
pocket  to  catch  water  and  dust,  by  forming  a step  in  the  sill  itself. 

2.  The  windows  should  be  made  entirely  of  wire  glass,  with  sheet 
metal  or  metal-covered  sash,  hung  in  metal  or  metal-covered  frames. 
Clear  wire  glass  can  be  used  if  desired. 

3.  On  the  inside  of  the  window  there  should  be  a sliding  shutter, 
either  of  wood  covered  with  sheet  metal  or  of  sheet  metal  such  as 
that  described  for  the  outside.  If  the  outer  wall  is  furred,  a pocket 
could  be  made  between  the  furring  and  the  wall,  so  that  the  inside 
shutters  could  be  slid  sidewise. 

It  is  probable  that  under  a fairly  bad  exposure  to  fire  the  outer 
shutters  here  described  would  be  so  damaged  that  they  would  have 
to  be  removed.  In  a conflagration  they  would  probably  be  warped 
to  such  an  extent  as  to  let  the  heat  in,  and  possibly  to  soften  the  wire 
glass  and  damage  the  windows  themselves,  so  that  they  also  might 
have  to  be  renewed' — at  least  so  far  as  the  sash  were  concerned.  But 
it  is  very  doubtful  if  any  conflagration  would  ever  get  through  the 
sash,  much  less  through  the  inside  shutters.  Any  damage  to  the 
window  protection,  however,  would  be  a very  small  matter  compared 
with  the  total  destruction  of  the  contents  of  the  building  and  a 
damage  of  65  to  80  per  cent  to  the  building  itself. 

Window  protection  of  the  kind  just  described  could  be  so  designed 
that  it  would  not  be  objectionable  even  on  the  principal  fronts  of 
buildings.  The  San  Francisco  and  Baltimore  fires  have  demon- 
strated that  all  the  exterior  openings  of  even  fireproof  buildings  need 
protection.  It  would  seem  that  the  time  has  arrived  when  building 
ordinances  should  require  it. 

If  to  the  triple  window  protection  described  above  a window 
sprinkler  with  adequate  water  supply  is  added,  a defense  which 
will  probably  not  only  be  adequate  for  its  purpose,  but  which  will 
suffer  small  damage  itself,  will  be  provided.  This  system  of  protec- 
tion, while  it  has  never  been  applied,  can  be  applied  at  a cost  which 
is  not  prohibitive,  especially  if  unnecessary  and  expensive  finish  is 
omitted. 

Practically  all  the  fireproof  buildings  in  San  Francisco  were  un- 
shuttered. Many  nonfireproof  buildings  were  partially  shuttered, 
but  no  building,  except  that  of  the  Pacific  States  Telephone  and  Tele- 


124 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


graph  Company  on  Bush  street,  was  completely  shuttered.  Although 
every  opening  in  this  building  was  protected,  it  is  not  certain  that 
the  fire  did  not  find  its  way  into  the  building  through  some  of  them 
in  spite  of  the  protection.  The  protection  of  individual  openings 
apparently  was  not  quite  heavy  enough.® 

The  view  of  the  main  front  of  this  building  (PI.  XLI,  A)  shows 
plainly  that  it  was  not  severely  attacked  by  the  flames,  yet  it  prob- 
ably would  have  resisted  such  an  attack  a good  deal  better  than  the 
fagades  of  many  other  buildings.  The  exterior  architraves  of  most 
of  the  windows  are  of  solid  molded  brickwork,  and  the  amount  of 
hollow  terra  cotta  in  the  exterior  front  is  reduced  to  a minimum,  so 
that  this  building  would  probably  not  have  suffered  quite  as  much 
as  the  average,  even  if  the  fire  test  from  the  outside  had  been  fully 
as  severe. 

FIREPROOF  VAULTS. 

It  would  seem  that  the  question  of  so-called  fireproof  vaults  in 
commercial  office  buildings  should  also  receive  some  attention.  The 
failure  of  such  vaults  in  San  Francisco  is  absolutely  inexcusable. 
The  fact  that  they  were  so  flimsy  was  not  due  to  any  lack  of  available 
knowledge  as  to  how  a fireproof  vault  should  be  built ; the  only 
motive  that  can  be  imagined  for  the  erection  of  such  vaults  is  parsi- 
monious and  criminal  economy.  (See  PI.  LII.) 

CONSTRUCTIONS  AND  MATERIALS  RECOMMENDED  FOR  EARTH- 
QUAKE LOCALITIES. 

For  every  tall  building  the  best  type  of  construction  is  undoubt- 
edly a steel  frame,  but  it  should  be  thoroughly  braced  in  much  the 
same  way  as  in  the  Call  Building,  where  the  steel  bracing  undoubt- 


a Since  the  above  was  written  the  following  information  has  been  received  from  Cali- 
fornia, through  the  courtesy  and  cooperation  of  Capt.  M.  L.  Walker  and  Capt.  William 
Kelly,  both  of  the  Corps  of  Engineers  : 

The  rolling  shutters  on  the  Bush  street  building  of  the  Pacific  States  Telephone  and 
Telegraph  Company  were  made  of  interlocking  slats  crimped  out  of  heavy  sheet  iron, 
the  shutter  as  a whole  sliding  at  the  sides  of  the  opening  in  heavy  iron  guides.  Cap- 
tain Kelly  thinks  they  were  made  of  No.  22  iron.  I do  not  believe,  personally,  that  these 
shutters  withstood  the  direct  impact  of  fierce  flame  for  a great  length  of  time  ; they  would 
have  warped  and  pulled  apart  so  as  to  let  the  flame  in.  The  view  of  the  Bush  street 
front  of  this  building  (shown  in  PI.  XLI,  A)  would  indicate  that  there  was  no  direct 
attack  by  the  flame  from  the  outside,  and  there  is  every  reason  to  believe  that  the  plate 
glass  on  the  inside  stood  long  enough  to  prevent  the  shutters  from  receiving  any  serious 
attack  from  the  flames  of  the  interior  fire.  It  is  probable,  however,  that  these  shutters 
are  fully  as  efficient  as  the  rolling  shutters  made  by  other  manufacturers  out  of  continu- 
ous sheets  of  corrugated  iron  riveted  together  along  the  edges.  The  continuous  sheets 
have  to  be  of  rather  light  metal,  in  order  to  make  them  practicable  ; and  when  subjected 
to  any  great  amount  of  heat  they  invariably  pull  apart  along  the  lines  of  rivet  holes — a 
weakness  which  was  clearly  illustrated  in  the  Baltimore  fire.  There  would  seem  to  be  no 
doubt,  however,  that  rolling  shutters  of  either  type  used  on  the  outer  windows  of  a 
building  would  effectually  prevent  ignition  from  radiant  heat  due  to  a fire  in  a neighbor- 
ing building.  They  would  also,  of  course,  resist  for  a time  the  actual  impact  of  flame, 
but  I am  personally  of  the  opinion  that  they  could  not  resist  this  form  of  attack  for  very 
long. 


RECOMMENDATIONS  IN  RELATION  TO  CONSTRUCTION.  . 125 

edly  saved  the  masonry.  In  such  buildings  as  the  new  Chronicle 
and  the  Monadnock  the  effect  of  the  vibration  was  really  resisted  by 
the  masonry,  which  was  much  shattered.  Some  of  it  was  precipitated 
into  the  street  from  the  new  Chronicle  Building,  the  Rialto  Building, 
and  others.  It  is  not  at  all  certain  that  the  steel  frames  of  these 
buildings  have  not  also  been  seriously  damaged  by  the  earthquake. 
Naked  steel  frames  of  the  same  type  came  through  without  serious 
damage,  but  they  did  not  suffer  the  additional  stresses  due  to  the 
vibration  of  a great  load  of  masonry,  floor  construction,  and  con- 
tents in  the  upper  stories,  as  did  the  finished  buildings.  It  is  not 
right  to  run  the  risk  of  precipitating  the  masonry  into  the  street  on 
the  heads  of  passers-by,  as  would  have  happened  at  the  unbraced 
steel-frame  buildings  had  the  earthquake  occurred  at  a later  hour  in 
the  day.  Besides,  if  the  strength  of  the  building  is  dependent  on  the 
masonry,  which  is  seriously  shattered  by  the  stresses  that  it  is 
expected  to  resist,  the  factor  of  safety  against  general  collapse  is 
manifestly  too  small.  The  steel-frame  construction  should  therefore 
be  thoroughly  braced.  In  my  judgment,  to  obtain  the  best  results  it 
should  also  be  inclosed  with  walls  of  reenforced  concrete,  in  which 
case  it  would  be  almost  impossible  to  throw  the  walls  off.  The  proper 
artistic  treatment  of  this  material  in  a place  like  San  Francisco  would 
seem  to  be  a very  important  problem  for  the  architects.  The  great 
utility  of  reenforced  concrete  in  earthquake  shocks  can  not  be  denied. 
Where  steel-frame  buildings  are  to  be  finished  with  ordinary-miasonry 
walls,  however,  complete  bonding  of  all  face  bricks  with  full  header 
courses  should  be  absolutely  required.  No  other  form  of  bond  is 
adequate.  Nothing  but  Portland-cement  mortar  should  be  allowed  in 
any  part  of  the  structure.  The  masonry  should  be  tied  to  the  steel 
frame  in  the  very  best  possible  way,  and  much  more  securely  than  is 
ordinarily  the  case. 

For  buildings  of  moderate  height,  say  up  to  125  feet  as  an  extreme 
limit,  reenforced  concrete  alone  can  undoubtedly  be  so  designed  as  to 
give  very  good  results  when  subjected  to  either  earthquake  or  fire. 
But  the  bracing  of  a reenforced-concrete  building  of  any  height  to 
resist  earthquake  is  a matter  for  serious  study.  The  problem  can  be 
solved,  but  it  has  not  been  solved  yet. 

Any  building  of  considerable  height,  in  an  earthquake  country, 
should  have  as  little  mass  in  the  superstructure  as  possible,  consistent 
with  other  necessary  qualities.  But  this  limiting  of  mass  does  not 
mean  that  the  flimsy  floors  and  partitions  heretofore  in  use  should  be 
continued.  In  fact,  to  make  the  buildings  proof  against  both  earth- 
quake and  fire  it  is  probable  that  they  will  have  to  be  at  least  as 
heavy  as  they  have  been,  but  changes  in  distribution  of  the  mass 
could  advantageously  be  made. 


126 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


For  the  ordinary  commercial  building,  where  brick  walls  and 
wooden  joists  would  ordinarily  be  used,  I am  of  the  opinion  that 
the  use  of  reenforced  concrete  would  be  the  safest  and  most  practica- 
ble solution  in  a place  like  San  Francisco.  Where  reenforced  con- 
crete is  used  throughout,  whether  the  building  is  very  tall  or  not, 
great  care  should  be  taken  with  the  design  and  execution  of  the  con- 
nections between  the  columns  and  the  members  of  the  floor  system. 
There  should  be  heavy  knee  braces  for  the  connection  of  all  girders 
and  beams,  and,  wherever  possible,  portal  bracing  in  the  shape  of 
reenforced-concrete  arches  should  be  introduced.  Of  course  the 
amount  of  this  work  that  needs  to  be  done  depends  on  the  circum- 
stances in  each  individual  case,  such  as  the  height  of  the  building, 
its  horizontal  area,  the  kind  of  material,  the  dead  weight  in  the 
upper  stories,  etc. 

The  opposition  of  the  bricklayers’  union  and  similar  organizations 
has  hitherto  prevented  the  use  of  reenforced  concrete  in  San  Fran- 
cisco for  all  parts  of  buildings.  This  action  of  the  labor  unions  has 
probably  cost  the  city  a good  deal,  and,  should  it  be  continued,  will 
cost  a great  deal  more  in  the  future. 

From  the  effect  on  the  fortifications,  and  on  monolithic  and  massive 
concrete  structures  elsewhere,  as  indicated  by  the  details  taken  from 
the  report  of  Professors  Marx  and  Wing,  it  seems  justifiable  to  con- 
clude that  a solid  monolithic  concrete  structure  of  any  sort  is  secure 
against  serious  damage  in  any  earthquake  country,  unless  it  should 
happen  to  lie  across  the  line  of  the  slip ; in  that  case  the  damage 
might  be  fatal,  or  it  might  not,  depending  altogether  on  the  amount 
of  the  slip  and  the  intensity  of  the  forces  that  accompanied  it. 

It  would  seem  that  earth  dams  of  ample  size  and  with  good  founda- 
tions are  also  secure  against  fatal  damage  unless  they  are  traversed 
by  the  slip.  Even  in  the  latter  case  the  damage  would  appear  to  be 
not  always  fatal ; that  it  would  never  be  fatal,  however,  would  be  a 
rash  assertion  to  make.  It  is  unsafe  to  say  that  any  sort  of  structure 
could  be  built  so  that  geologic  faulting  could  occur  immediately 
underneath  it  without  doing  serious  damage.  As  a matter  of  fact, 
however,  most  structures  in  an  earthquake  country  would  not  lie  on 
the  line  of  a fault,  and  it  seems  quite  certain  that  in  such  cases 
well-constructed  earth  dams  and  solid  monolithic  masses  of  concrete, 
whether  large  or  small,  would  escape  serious  injury. 

THE  MINIMIZING  OF  FIRE  LOSSES. 

A study  of  the  results  of  the  Baltimore  and  San  Francisco  fires, 
especially  in  connection  with  the  statements  of  adjusted  losses  at 
Baltimore,  readily  discloses  the  following  facts: 

In  the  first  place,  the  contents  of  the  fireproof  buildings  were  a 
total  loss.  In  many  buildings  the  contents  might  probably  be  worth 


127 


THE  MINIMIZING  OF  FIRE  LOSSES. 

more  than  the  structure  itself,  especially  if  any  attempt  is  made  to 
fix  the  value  of  records  and  papers  that  can  not  be  duplicated.  In 
the  second  place,  the  buildings  themselves  suffered  a damage  exceed- 
ing 65  per  cent,  and  in  San  Francisco  probably  amounting  to  almost 
80  per  cent.  A study  of  the  items  entering  into  this  damage  dis- 
closes the  fact  that  a very  large  proportion  of  it  is  due  to  the  loss 
of  the  architectural  finish,  such  as  face  brickwork,  ornamental  terra 
cotta,  and  stonework  on  the  exterior;  marble  dadoes,  columns,  and 
other  finish  on  the  interior ; wooden  door  and  window  frames,  wooden 
doors  and  windows,  ornamental  grillwork,  etc.  If  the  fireproof- 
building problem  is  to  be  solved  in  such  a manner  that  conflagrations 
will  not  cause  serious  losses,  it  would  seem  that  radical  revision  of 
the  method  of  finish  is  necessary.  As  the  finish  must  practically  be 
a total  loss  anyway,  it  should  be  so  devised  that  it  can  be  replaced 
at  small  expense.  This  requirement,  however,  makes  it  impossible 
to  adopt  a material  for  the  construction  which,  as  the  architects  say, 
finishes  itself— because,  if  the  exposed  surface  is  destroyed,  the 
material  becomes  a total  loss.  It  would  seem  that  for  the  exterior 
of  the  structure,  walls  well  built  of  good,  common  brick,  laid  in 
Portland-cement  mortar,  or  else  of  reenforced  concrete,  could  be 
finished  on  the  outside  with  stucco,  pebble  dash,  or  some  similar 
material.  The  opportunity  for  the  effective  use  of  colors  here  would 
be  very  great.  If  the  buildings  were  exposed  to  a fire,  the  exterior 
finish  would  probably  be  a total  loss,  but  its  value  in  dollars  and 
cents  is  small.  The  fire  might  even  strip  it  off  and  cause  serious  spall- 
ing to  the  main  wall  underneath,  but,  even  so,  the  operation  of  renew- 
ing the  finish  would  furnish  adequate  repairs  for  the  main  wall  itself. 
On  the  other  hand,  if  face  brick  or  stone  or  ornamental  terra  cotta 
be  spalled,  the  loss  is  total;  the  original  finish  can  not  be  renewed, 
except  by  tearing  the  wall  down  and  rebuilding  it.  On  the  interior, 
combustible  trim  of  all  kinds  should  be  eliminated  and  marble  or 
stone  finish  should  be  securely  protected  from  the  access  of  fire. 
Enameled  bricks  and  enameled  tiles  should  also  be  made  secure 
against  not  only  the  direct  access  of  fire  but  the  effects  of  high  tem- 
peratures however  applied.  Instead  of  marble  wall  finish  or  enam- 
eled bricks  or  tiles,  wall  plaster  of  a good  quality,  finished  with 
enamel  paint,  furnishes  a perfectly  satisfactory  substitute,  so  far 
as  utility  and  sanitary  qualities  are  concerned.  If  such  finish  is 
destroyed  b}7  fire,  its  renewal  is  a matter  of  relatively  small  cost. 

All  interior  partitions  should  be  so  solidty  constructed  that  there 
would  be  no  question  whatever  of  a fire  ever  getting  through  them. 
That  ought  to  be  absolutely  impossible.  Stairways,  stairway  halls, 
and  other  places  where  elevator  grills,  ornamental  balustrades,  etc., 
might  be  used  should  be  so  located  that  no  fire  would  ever  get  into 
them,  and  they  should  be  kept  absolutely  free  of  combustible  matter 


128  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

of  all  sorts  and  descriptions.  Wooden  floor  finish  should  not  be 
allowed  in  any  portion  of  the  building.  All  doors,  door  frames,  win- 
dow frames,  and  window  sash  should  be  of  metal  or  of  wood  covered 
with  metal.  All  important  openings  should  have  doors  on  both  sides 
of  the  wall,  the  idea  being  to  so  design  the  interior  of  the  building 
that  a fire  starting  in  any  one  room  could  be  left  to  burn  itself  out 
not  only  without  being  communicated  to  other  rooms  or  to  the  corri- 
dors, but  also  without  causing  any  great  money  loss  to  the  building 
itself  in  the  room  or  rooms  where  the  fire  occurs.  The  interior  con- 
struction of  the  building  should  be  such  that,  should  a fire  by  any 
chance  be  introduced  from  the  outside,  it  could  be  confined  absolutely 
to  the  room  or  rooms  to  which  it  finds  access.  Such  a thing  as  a 
conflagration  sweeping  through  a building  can  be  made  impossible 
at  reasonable  expense,  provided  unnecessary  architectural  finish  is 
omitted  and  the  money  ordinarily  expended  on  it  is  applied  to  other 
things. 

Even  such  a building,  however,  might  have  a shutter  left  partly 
open,  or  some  other  of  the  various  fire-resisting  devices  might  be  left 
in  such  condition  as  to  defeat  the  purpose  for  which  it  was  installed ; 
so  that  if  the  building  contains  a large  amount  of  combustible  con- 
tents, it  should  still  be  provided  with  sprinklers.  The  municipal 
water  supply  should  be  under  sufficient  pressure  to  supply  the 
sprinkler  system.  In  a city  like  San  Francisco  an  artesian  well  and 
fire  pump  in  each  building  should  be  provided  for  the  same  purpose, 
If  possible.  Even  then,  if  there  is  a conflagration  raging,  the  me- 
chanical staff  of  the  building  and  as  many  more  men  as  can  be 
obtained  should  be  kept  on  duty  inside  the  building,  watching  for 
points  of  weakness  and  extinguishing  fires  should  any  begin.  A 
small  amount  of  water  and  a small  force  of  men  would  suffice  for 
this  duty  in  a building  constructed  as  described. 

It  appears  that  in  San  Francisco  a number  of  owners  who  were 
organizing  forces  for  the  active  defense  of  their  buildings  were 
driven  out  by  the  police  and  military  authorities  in  accordance  with 
instructions  from  the  municipal  authorities — no  doubt  to  prevent 
looting  and  also  with  a view  of  saving  people  from  the  effects  of  the 
dynamiting.  It  would  seem,  however,  that  in  some  cases  proper 
judgment  was  not  exercised,  and  that  some  buildings  might  have  been 
saved  themselves  and  might  also  have  acted  as  barriers  to  the  further 
progress  of  the  flames  if  their  occupants  had  been  permitted  to  carry 
out  their  plans.  For  good  illustrations  of  what  can  be  done  in  this 
way  one  need  point  only  to  the  post-office  building,  the  mint,  and  the 
appraisers’  stores.  There  is  also  every  reason  to  believe  that  a more 
or  less  active  defense  was  carried  on  in  the  Kohl  Building ; otherwise 
it  must  have  suffered  more  severely  than  it  did.  As  it  was,  however, 
this  building  was  saved  with  slight  damage. 


EARTHQUAKE  INSURANCE, 


129 


A fire-resisting  building  is,  in  one  sense,  exactly  analogous  to  a 
fortification — it  needs  a garrison  to  make  it  thoroughly  effective. 
There  is  this  difference,  however,  that  a fire-resisting  building  can 
be  made  so  effective  in  itself  that  a relatively  small  garrison  can 
save  it.  In  my  judgment,  a building  thoroughly  well  constructed 
along  the  lines  indicated  in  this  report  would  stand  in  a conflagration 
such  as  that  which  occurred  in  San  Francisco,  preserve  its  contents, 
and  suffer  a loss  to  its  own  structure  and  finish  not  exceeding  15  per 
cent.  Until  a result  approximating  this  degree  of  endurance  is 
achieved,  it  is  hardly  fair  to  say  that  the  u modern  fire-resisting  build- 
ing ” is  a success,  except  in  so  far  as  it  enables  a sufficiently  tall  struc- 
ture to  be  erected  on  a piece  of  valuable  real  estate  to  furnish  an 
adequate  return  for  the  entire  investment,  and  even  this,  statement  is 
true  only  as  long  as  the  building  does  not  happen  to  be  attacked  by 
a conflagration. 

EARTHQUAKE  INSURANCE. 

It  would  seem  that  in  a place  like  San  Francisco  it  would  be  sound 
policy  for  the  business  men  to  form  a mutual  earthquake  insurance 
company  on  lines  similar  to  those  of  the  mutual  fire  insurance  com- 
panies. They  should  employ  competent  experts  to  draft  specifica- 
tions and  evolve  types  of  designs  not  in  conflict  with  the  municipal 
ordinances  for  buildings  specially  planned  to  resist  earthquake.  To 
be  admitted  to  the  benefits  of  the  mutual  earthquake  insurance  com- 
pany an  owner  should  be  required  to  conform  to  the  standard  plans 
and  specifications.  In  my  judgment,  there  is  every  reason  to  believe 
that  such  an  enterprise  could  be  made  successful  and  that  it  would 
result  in  having  available  at  all  times  a fund  for  making  good  any 
earthquake  damage.  It  is  probable  that  the  premiums  that  would 
have  to  be  charged  by  such  a mutual  insurance  company  would  be 
found  to  be  no  greater  than  those  that  are  charged  for  fire  risks 
in  large  cities. 

SUMMARY. 

It  will  be  apparent  that  much  of  the  information  presented  in  a 
report  like  this  one  is  necessarily  hearsay.  So  far  as  the  history  , of 
the  fire  is  concerned,  this  indefiniteness  can  not  be  avoided,  and  the 
details  of  the  damage  itself  could  be  verified  only  by  a prolonged 
stay  in  the  ruined  city  and  a close  inspection  of  the  ruins  of  every 
building  at  every  stage  of  the  process  of  cleaning  up.  It  is  to  be 
hoped  that  the  technical  men  engaged  on  this  work  will  keep  a com- 
plete and  accurate  record  of  all  details  of  every  sort,  which  will  be 
available  for  future  reference.  It  is  believed,  however,  that  enough 
evidence  was  collected  at  first  hand  to  abundantly  justify  every  con- 


130 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


elusion  and  broad  statement  contained  in  this  report.  The  only  doubt 
in  my  mind  is  whether  the  damage  may  not  have  been  really  greater 
than  it  appears. 

Extreme  caution  should  be  observed  in  drawing  general  conclu- 
sions from  any  individual  case  of  damage  in  a great  conflagration. 
For  instance,  the  way  in  which  misleading  conclusions  can  readily 
be  reached  is  indicated  in  the  discussion  of  the  relative  merits  of  terra 
cotta  and  concrete  for  fireproof  floor  construction.  The  records  of  the 
fire,  rightly  read,  would  prove  that  both  concrete  and  burned  clay  are 
efficient  as  materials,  but  that  the  method  of  application  of  both  is 
open  to  severe  criticism.  That  hasty  and  ill-founded  conclusions 
have  been  reached  is  only  too  evident  from  the  articles  which  have 
appeared  since  the  San  Francisco  disaster. 

It  is  also  necessary  that  extreme  caution  should  be  observed  in 
drawing  conclusions  in  regard  to  the  effect  of  the  earthquake.  Reen- 
forced concrete  proved  itself  superior  to  brickwork  beyond  any  doubt. 
There  is  every  reason  to  believe  that  for  buildings  of  moderate  height 
reenforced  concrete  can  be  so  designed  that  it  will  be  quite  as  effi- 
cient as  a steel  frame;  but  it  should  be  remembered  that  this  propo- 
sition was  not  proved,  because  there  was  no  reenforced-concrete  build- 
ing of  considerable  height  in  the  entire  district  affected.  Again,  the 
fact  that  steel  frames  stood  up  during  the  earthquake  does  not  prove 
that  they  are  earthquake  proof.  The  framing  of  the  tower  of  the 
Union  Ferry  Building  suffered  almost  fatal  damage,  yet  it  stood  up. 
The  Call  Building  proved  the  efficiency  of  stiff  and  adequate  steel 
bracing;  but  many  of  the  other  commercial  steel-skeleton  buildings 
showed  very  clearly  the  need  of  it.  The  fact  that  some  of  the  tall 
buildings  are  now  out  of  plumb  is  no  proof  that  they  are  damaged; 
very  few  such  structures  ever  are  plumb,  and  if  the  deviation  is  not 
very  great  it  is  quite  possible,  even  probable,  that  the  building 
was  erected  out  of  plumb.  The  condition  of  the  masonry  in  wall 
piers,  however,  gives  ground  enough  for  uneasiness.  It  is  safe  to 
say  that  a well-braced  steel  frame  is  proof  against  ordinary  earth- 
quakes, but  to  point  to  the  actual  commercial  steel- frame  structure  in 
San  Francisco  as  a triumph  of  the  ordinary  type  of  steel  frame,  in 
advance  of  the  careful  detailed  inspection  of  the  steel  work  by  com- 
petent engineers,  is  premature,  to  say  the  least. 


THE  EARTHQUAKE  AND  FIRE  AND  THEIR  EFFECTS  ON 
STRUCTURAL  STEEL  AND  STEEL-FRAME  BUILDINGS. 


By  Frank  Soule. 


THE  EARTHQUAKE. 

^ GEOLOGIC  FEATURES. 

On  the  morning  of  April  18,  1906,  central  California  experienced 
an  earthquake,  the  most  severe,  as  measured  by  its  results,  in  the  his- 
tory of  the  State.  The  seismograph  in  the  observatory  of  the  Uni- 
versity of  California,  at  Berkeley,  recorded  the  shock  as  beginning 
at  5 hours  12  minutes  6 seconds  a.  m.,  Pacific  standard  time,  and  as 
lasting  for  one  minute  and  five  seconds.  Its  severity  was  afterwards 
estimated  and  rated  as  IX  in  the  Rossi-Forel  scale  of  earthquake 
intensities.  Other  minor  shocks  followed  immediately  and  at  short 
intervals,  so  that  before  7 p.  m.  of  the  same  day  thirty-one  of  these 
had  been  registered  at  the  observatory.  Slight  shocks,  coming  suc- 
cessively after  longer  and  longer  intervals  of  time,  were  experienced 
during  several  weeks  following,  until  finally  the  earth’s  crust  in  Cali- 
fornia seemed  to  have  readjusted  itself  to  new  conditions  of  pressure 
and  equilibrium.  The  material  damage  from  the  earth  tremors  was 
inflicted  by  the  first  great  shock.  The  minor  ones  following  wrought 
no  injury,  except  to  throw  down  a few  tottering  walls  that  had  been 
racked  by  the  original  earthquake. 

For  many  years  the  leading  geologists  in  California  have  known 
that  a rift,  or  line  of  dislocation  in  the  earth’s  crust — called  in  com- 
mon parlance  an  “ earthquake  crack  ’’—starting  near  Point  Arena, 
extends  in  a straight  line,  at  least  400  miles  in  length,  in  a direction 
S.  35°  E.  (fig.  1,  p.  3).  Passing  under  the  ocean  bed  8 miles  west 
of  the  Golden  Gate,  the  rift  cuts  the  shore  again  at  Mussel  Rock,  runs 
along  the  reservoir  basins  of  the  Spring  Valley  Water  Company  and 
over  the  Coast  Range  of  mountains,  ignoring  surface  topography  in 
its  course,  and  extends  at  least  to  Mount  Pinos,  in  Ventura  County, 
and  probably  still  farther  to  Lake  Elsinore,  in  southern  California. 
This  great  “ fault  ” gives  abundant  geologic  evidence  of  having  been, 
in  the  remote  past,  the  locus  of  many  distinct  earthquake  movements 
and  disturbances. 


131 


132  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

It  was  a rupture  and  slip  along  this  fault,  plainly  evident  for 
nearly  200  miles,  that  shook  so  violently  the  thousands  of  square 
miles  of  the  earth’s  surface  in  central  California.  The  first  snap  and 
movement  of  the  crust  were  registered  at  the  observatory  of  the 
State  University  as  proceeding  from  south-southeast  to  north-north- 
west, or  about  parallel  to  the  fault.  This  movement  was  there  re- 
corded as  over  3 inches  horizontally,  and  was  accomplished,  as  esti- 
mated by  the  California  earthquake  investigation  commission,  in  one 
second  of  time.  The  vertical  movement  at  the  same  place  and  time 
was  believed  to  be  about  1 inch.  Professor  Omori,  the  distinguished 
Japanese  seismologist,  also  estimated  the  vibration  in  San  Francisco 
to  be  3 inches  in  one  second. 

Instantly  following  this  first  snap  were  rebounds,  reactions,  and 
terranean  reverberations  from  all  parts  of  the  greatly  disturbed  area 
on  either  side  of  the  fault  trace,  which  made  the  record  on  the  seis- 
mograph resemble  a tangled  spider’s  web.  It  was  this  part  of  the 
earthquake— the  temblors — that  created  and  continued  the  racking 
vibrations,  the  twistings,  and  the  wrenchings  that  brought  down 
chimneys,  walls,  and  towers. 

Members  of  the  California  earthquake  investigation  commission 
advanced  the  belief  that  the  first  break,  slip,  and  shock  in  the  crust 
began  at  the  northwest  extremity  of  the  fault  trace,  and  that  from 
this  point  the  rupture  and  shearing  extended  progressively  toward 
the  southeast.  This  view  seems  to  be  borne  out  by  later  investi- 
gations, and  certainly  the  greatest  disturbances  on  the  line  of  the 
fault  were  at  and  near  its  northern  extremity.  The  earthquake  was 
felt  to  a greater  or  less  degree  over  a vast  extent  of  territory,  stretch- 
ing from  Coos  Bay,  in  Oregon,  to  Los  Angeles,  in  southern  Califor- 
nia, and  from  western  Nevada  over  the  greater  part  of  middle  Cali- 
fornia, and  even  out  to  sea.  Although  not  noticeable  to  the  senses,  it 
was  recorded  on  seismographs  in  Washington,  D.  C. ; Tokyo,  Japan; 
and  Potsdam,  Germany. 

A STUDY  OF  THE  EFFECT  OF  NATURAL  FEATURES  ON  THE 
INTENSITY  OF  DESTRUCTION. 

DISTANCE  FROM  THE  FAULT  LINE. 

The  actual  area  of  destruction  was  about  400  miles  long  (from 
north  to  south)  and  50  miles  wide  on  either  side  of  the  fault  trace. 
The  destruction  wrought  by  the  earthquake  in  its  severe  effects  was 
proportional  in  a way  to  the  nearness  of  the  locality  to  the  fault  trace, 
but  varied  greatly  according  to  the  character  of  the  rock  and  soil 
formation  throughout  the  disturbed  area. 

Directly  on  the  fault  trace  the  disturbance  and  destruction  were 
at  a maximum.  Many  buildings  and  other  structures  were  wrenched, 


SOIL  FORMATION. 


133 


twisted,  and  thrown  down  (PI.  X,  B)  ; fissures  were  opened  in  the 
earth  (Pis.  Ill,  IV)  ; trees  were  uprooted  and  thrown  to  the  ground, 
or  snapped  off,  leaving  their  stumps  in  a standing  position,  or  split 
from  the  ground  up  through  the  stock  to  the  branches  (PL  II). 
Roads  were  ruined  for  long  distances,  bridges  were  thrown  off  their 
abutments  (PI.  XI,  A ),  and  water  pipes  were  twisted,  telescoped, 
collapsed,  or  broken  (Pis.  IX;  X,  A).  Along  the  seashore  immense 
landslides  occurred,  throwing  vast  quantities  of  earth  and  rock  into 
the  sea.  (See  also  PI.  VIII,  B.) 

The  main  pipe  lines  of  the  Spring  Valley  Water  Company,  which 
were  depended  on  exclusively  to  supply  the  city  of  San  Francisco 
with  water,  as  well  as  the  distribution  system  of  this  company  in 
the  city,  were  broken  in  many  places,  and  the  supply  of  water  was 
absolutely  cut  off  for  a number  of  days  after  the  earthquake  (map 
PI.  LVI).  The  great  mains  leading  from  Pilarcitos,  San  Andreas, 
and  Crystal  Springs  lakes  were  all  badly  broken  (PL  LVII).  The 
Pilarcitos  conduit  in  particular,  which  ran  almost  along  the  fault 
trace,  was  completely  ruined  and  rendered  unfit  for  repair  (PL  IX). 
The  great  44-inch  water  main  crossing  the  San  Bruno  marsh  was 
thrown  down  from  its  supporting  trestles  in  a serpentine  line,  and 
broken  in  several  places. 

As  the  distance  from  the  fault  trace  increased,  the  violence  of  the 
disturbance  in  a general  way  diminished,  but  this  statement  must 
be  modified  by  saying  that  in  cities  and  towns  built  upon  the  alluvial 
soil  of  valleys  the  destruction  was  at  its  greatest,  as,  for  instance,  at 
Santa  Rosa,  about  20  miles  east  of  the  fault  trace,  in  the  Sonoma 
Valley  (Pis.  XIV,  B ; XVII,  A).  This  city,  built  upon  a deep, 
alluvial  soil,  was  more  severely  shaken  and  suffered  greater  damage, 
in  proportion  to  its  size,  than  any  other  town  in  the  State.  Scarcely 
a brick  or  stone  building  in  the  town  was  left  standing,  and  80 
people  were  killed. 

SOIL  FORMATION. 

The  destruction  wrought  by  the  earthquake  amounted  to  little  or 
nothing  in  well-built  structures  resting  upon  solid  rock,  and,  all 
other  things  being  equal,  increased  in  proportion  to  the  depth  and 
incoherent  quality  of  the  foundation  soil.  Thus  dwellings  in  Ber- 
keley, upon  the  solid  rock,  were  scarcely  disturbed,  while  those  on 
the  level  plain  of  Oakland,  4 miles  distant,  were  severely  shaken  and 
injured,  as,  also,  were  the  buildings  at  Leland  Stanford  Junior  Uni- 
versity (Pis.  XIV,  A;  XV;  XVI;  XVII,  B;  XVIII),  7 miles  dis- 
tant from  the  fault  trace;  at  San  Jose  (Pis.  XII,  B ; XIII,  R),  13 
miles  distant;  and  at  Agnew  (PL  XIII,  A),  12  miles  distant.  The 
town  of  Salinas  and  the  alluvial  valley  of  Salinas  River  were  also 
severely  shaken.  This  region  was  fissured  and  disturbed  more  than 
any  other  district  in  the  State. 

7171— Bull.  324—07 10 


134  THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 

In  order  to  get  a fair  understanding  of  the  effects  of  the  earth- 
quake in  San  Francisco,  a knowledge  of  the  geologic  formation  and 
the  different  soils  constituting  the  foundations  of  structures  is  neces- 
sary. The  city  and  county  of  San  Francisco  comprise  the  northern 
extremity  of  a long,  narrow  peninsula,  lying  south  of  the  Golden 
Gate,  between  the  Pacific  Ocean  on  the  west  and  the  southern  half 
of  San  Francisco  Bay  on  the  east.  (See  map,  PL  LVII.)  The 
boundary  line  between  this  county  and  San  Mateo  County  lies  about 
8 miles  south  of  the  Golden  Gate.  The  area  of  San  Francisco  County 
is  46^  square  miles.  The  population  of  the  city  on  April  1,  1906, 
was  estimated  to  be  460,000. 

The  site  of  the  city  has  at  least  four  different  soil  formations. 
Around  the  Bay  of  San  Francisco,  from  Telegraph  Hill  to  Mission 
Creek,  which  runs  from  west  to  east  and  empties  into  the  bay,  and 
on  both  shores  of  the  creek  is  a strip  which  was  originally  mud 
flats  and  overflowed  lands,  having  an  area  of  about  354  acres.  These 
tracts  have  been  gradually  filled  in  (especially  on  the  bay  shore 
and  the  northern  Mission  Creek  sides),  since  the  days  of  the  Ameri- 
can occupation,  by  encroachments  on  the  water  front,  due  to  business 
and  commercial  pressure,  and  wharves  and  docks,  warehouses,  fac- 
tories, manufacturing  establishments,  and  large  wholesale  houses 
have  been  built  on  these  filled-in  lands.  At  the  present  time  these 
large  areas  are  for  the  most  part  included  within  the  sea  walls  run- 
ning around  the  officially  established  water  front  nearly  as  far  as 
Mission  Creek.  They  are  known  as  “ made  lands,”  and  consist  of 
deep  layers  of  mud,  in  many  places  saturated  with  salt  water,  and 
overlain  by  sand,  trash,  etc.,  which  has  been  filled  in  upon  them. 

On  this  soil  were  built  nearly  all  the  commercial  and  wholesale 
business  structures  of  San  Francisco — such  as  the  Union  Ferry  Build- 
ing— many  large  hotels,  the  post-office,  the  branch  mint,  and  similar 
structures.  On  the  Mission  Creek  side  were  originally  very  large 
areas  of  marshes  that  have  been  filled  in  with  sand  from  adja- 
cent hills.  Adjoining  all  these  made  lands  is  the  comparatively 
level  ground,  composed  of  a natural  mixture  of  sand  and  clay,  formed 
by  the  wearing  of  the  hillsides  and  by  the  incoming  of  sands  drifted 
from  the  seacoast.  Upon  this  fringe  of  soil  next  to  the  made  lands 
were  built  many  of  the  largest  hotels,  tall  office  buildings,  and  expen- 
sive structures  of  brick,  stone,  and  steel. 

A ridge  of  rocky  hills  runs  from  the  northeast  corner  of  the  city, 
or  Telegraph  Hill,  southwestward  along  Russian  Hill,  Clay  Street 
Hill,  and  so  on,  to  Sutro  Heights.  These  hills  are  composed  largely 
of  indurated  clay,  shale,  and,  on  their  highest  summits,  serpentine 
and  other  rocky  formations.  A ridge  of  sand  hills  runs  through  the 
western  and  southwestern  portions  of  the  city  to  the  Pacific  Ocean. 
The  slopes  and  summits  of  the  hills  nearest  the  business  portion  of 


SOIL  FORMATION. 


135 


the  city  are  closely  built  residence  districts,  and  the  areas  toward  the 
Pacific  Ocean  are  covered  with  cottages,  more  and  more  sparsely 
placed,  to  the  boundaries  of  the  county. 

Adjoining  the  business  district  on  the  southwest  side,  along  Mis- 
sion Creek,  on  the  flat  sand  lots,  was  another  thickly  populated 
residence  section  known  as  “ south  of  Market  street.”  It  was  occu- 
pied almost  exclusively  by  wooden  buildings. 

More  than  90  per  cent  of  the  buildings  in  San  Francisco  were  of 
wood.  Almost  all  the  brick,  stone,  and  steel  structures  were  in  the 
congested  business  portions  of  the  city,  upon  or  very  near  the  made 
land.  Even  in  this  district  there  was  a large  percentage  of  wooden 
buildings.  High  steel  structures  of  the  most  modern  type  have 
been  erected  only  recently  in  San  Francisco,  and  the  number  of  them 
is  small,  not  exceeding  50. 

The  most  destructive  effects  of  the  earthquake  in  San  Francisco 
were  experienced  upon  this  made  land.  Wherever  buildings  were 
well  founded  on  wooden  jfiles  deeply  driven  into  the  mud— as,  for 
example,  the  Union  Ferry  Building — these  foundations  were  dis- 
turbed but  little  or  not  at  all ; and  where  the  superstructure  had  been 
well  and  strongly  put  up,  practically  no  damage  resulted.  Only  in 
poor  foundations  laid  directly  upon  “ filled-in  ”,  ground  on  the  raft 
principle,  or  in  buildings  that  were  poorly  constructed  or  under- 
pinned or  had  a weak  frame,  poor  brickwork,  or  brick  laid  dry  in 
poor  lime  mortar,  was  there  serious  damage  or  collapse. 

TheNUnion  Ferry  Building  (PI.  XL VI,  A),  with  the  exception  of 
its  high  tower,  was  little  injured,  and  the  level  of  its  floors  was  not 
perceptibly  changed.  At  the  same  time,  the  streets  at  its  front,  which 
rested  simply  on  the  made  soil,  were  rolled  into  waves  3 or  4 feet  in 
height.  So  far  as  the  writer  is  aware  no  foundations  that  had  been 
properly  established  were  in  any  considerable  degree  injured  by  the 
earthquake;  nor  was  any  structure  of  brick  or  stone,  iron  or  steel, 
that  was  well  designed  and  constructed,  greatly  damaged.  Some 
chimneys  and  cornices  were  thrown  down,  but  until  the  fire  had 
passed  over  the  region  the  structures  remained  ready  for  use.  This 
statement  applies  especially  to  the  wooden-frame  structures  through- 
out the  residence  part  of  the  city,  where  the  only  losses  were  those  of 
chimneys  and  plaster. 

On  the  made  land  in  the  business  portion  of  the  city  there  had 
been  erected  in  early  days  many  light  wooden  buildings,  which 
rested  on  simple  timber  underpinning  founded  on  the  filled-in  mate- 
rial. Many  of  these  structures  collapsed,  but  this  result  was  due  to 
their  imperfect  foundations  and  weak  construction  rather  than  to  the 
severity  of  the  earthquake.  Numerous  structures  in  this  district 
had  been  built  of  dry  brick  or  stone  laid  in  common  lime  mortar, 
and  their  beams,  girders,  and  columns  had  not  been  anchored  to  the 


136 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


walls.  Such  walls  commonly  collapsed,  and  the  brick  were  found 
afterwards  with  dry,  clean  surfaces,  the  mortar  having  no  adhesion. 
(See  PL  XXI,  A.)  On  the  other  hand,  walls  that  had  been  laid 
in  Portland-cement  mortar,  with  brick  thoroughly  wetted  and  all 
parts  well  bonded  together,  stood  the  trial  perfectly  and  are  stand- 
ing to-day. 

Tall,  steel-frame,  stone-exterior  office  buildings  of  the  class  A type 
that  were  founded  either  on  well-driven  piles  or  on  concrete  slabs 
suffered  no  very  serious  injury  by  the  earthquake.  With  the  excep- 
tion of  a crack  here  and  there  in  a stone  pier,  arch,  or  stairway,  or  a 
block  of  veneer  loosened  or  dropped  from  a front,  they  remained 
entirely  serviceable,  so  far  as  the  earthquake  effect  was  concerned. 
An  excellent  example  of  this  class  of  buildings,  and  one  that  is 
exceedingly  instructive,  as  it  passed  through  the  earthquake  but 
escaped  the  fire  that  ravaged  San  Francisco,  is  the  TJnion  Savings 
Bank,  in  Oakland,  at  the  corner  of  Broadway  and  Thirteenth  street. 
This  building  is  a steel-frame,  stone-veneered  structure,  having  11 
stories  and  a basement.  It  is  founded  upon  separate  concrete  blocks 
and  piers  which  rest  upon  a strong  soil  of  mixed  sand  and  clay.  This 
structure  was  practically  uninjured. 

Buildings  in  San  Francisco  which  rested  upon  foundations  of  sand 
in  natural  place  were  not  injured  by  the  shock,  except  where  the  sand 
was  on  a hillside  or  had  opportunity  to  spread  and  flow.  In  such 
places  buildings  of  either  masonry  or  wood  were  badly  shaken. 
Where  the  buildings  rested  upon  good,  hard  soil,  as  on  the  hillsides 
or  summits,  practically  no  injury  was  done  with  the  exception  of  the 
loss  of  chimneys  and,  in  some  buildings,  of  plaster.  A first-class 
building  of  stone,  brick,  concrete,  or  steel  frame  in  such  situation 
seems  absolutely  proof  against  any  earthquake  of  no  greater  severity 
than  the  one  under  discussion. 

THE  FIRE. 

GENERAL  DESCRIPTION. 

Immediately  after  the  first  shock  of  the  earthquake  sixteen  alarms, 
of  fire,  from  widely  separated  localities,  were  turned  in  to  the  central 
station.  The  causes  of  these  fires  were  directly  traceable  to  earth- 
quake effects,  such  as  the  upsetting  of  oil  lamps  and  oil  and  gasoline 
stoves,  the  contact  of  combustible  material  with  lamps  and  gas  jets, 
the  rupturing  of  chimneys  and  flues,  the  scattering  of  chemicals,  such 
as  phosphorus,  and  the  upsetting  of  boilers,  furnaces,  etc.  It  is 
claimed  that  currents  of  electricity  did  not  originate  any  fire.  Either 
the  generators  were  disabled  or  the  attendants  switched  off  the 
currents. 


GENERAL  DESCRIPTION  OF  THE  FIRE. 


137 


The  death  of  Mr.  Sullivan,  the  chief  of  the  fire  department,  which 
was  caused  by  the  falling  of  a mass  of  brick  from  a chimney  while 
he  lay  ill  in  bed,  was  a most  unfortunate  accident,  as  the  city  was 
thereby  deprived  of  his  excellent  knowledge  and  skill  as  a fire  fighter. 
The  fire  department,  although  it  responded  promptly  to  the  calls 
and  was  composed  of  brave  and  efficient  men,  with  excellent  appara- 
tus, was  disconcerted  by  the  loss  of  its  chief  and  paralyzed  in  its 
action  by  the  almost  complete  rupture  and  disintegration  of  the 
water  system.  The  city  mains  were  so  thoroughly  broken  that  in  a 
short  time  not  only  could  no  water  be  obtained  for  the  extinguish- 
ment of  fires,  but  for  a number  of  days  little  water  could  be  had  for 
domestic  use,  and  the  people  were  compelled  to  rely  on  a few  wells 
that  remained  available. 

In  private  dwellings  incipient  fires  were  quickly  extinguished  by 
individual  effort ; but,  because  of  the  early  hour,  the  fires  which  started 
in  the  great  downtown  business  houses,  factories,  etc.,  “ south  of 
Market  street,”  grew  to  alarming  proportions  before  anyone  could 
reach  and  conquer  them.  With  the  exception  of  the  private  water 
supplies,  such  as  wells  (see  map,  PI.  LVI) , pumping  systems,  etc.,  pos- 
sessed by  a few  establishments,  there  were  no  means  of  extinguishment. 
Within  three  hours  after  the  earthquake  nine  fires  were  in  full  con- 
flagration between  66  The  Mission  ” ° and  the  water  front  south  of 
Market  street.  At  first  there  was  little  or  no  wind  to  fan  the  flames, 
but  the  great  heat  soon  drew  in  a current  of  air  which  continually 
increased,  and,  varying  from  one  point  to  another,  swept  the  flames 
first  in  this  direction  and  then  in  that.  By  Wednesday  noon  the 
fire  had  consumed  nearly  a square  mile  of  the  city  on  the  south  side 
of  Market  street,  and  on  the  afternoon  of  the  same  day  it  broke  across 
to  the  north  side,  in  the  vicinity  of  the  high  steel  Call  (Claus  Spreck- 
els) , Examiner,  and  Chronicle  buildings.  Thence  the  fire  veered 
with  the  wind,  burning  northward  and  westward  through  China- 
town, and  joined  its  destructive  energy  with  that  of  a separate  col- 
umn of  fire  that  had  swept  up  from  the  lower  end  of  Market  street 
and  the  water  front.  The  column,  driven  by  the  wind,  ate  its  way 
rapidly  through  the  residence  portion  of  the  city,  which  was  built 
of  wood  and  hence  was  consumed  like  tinder.  Three  hours  after  the 
conflagration  had  begun  a corps  of  dynamiters  was  organized,  but  as 
no  such  body  had  existed  in  the  fire  department,  it  was  necessarily 
composed  of  volunteers  and  amateurs.  These  men  fought  the  flames 
with  great  bravery,  but  with  little  skill,  and  their  endeavors  to  arrest 
the  progress  of  the  fire  by  throwing  structures  down  in  its  path  were 

° “ The  Mission  ” is  a well-known  locality  in  the  city  of  San  Francisco.  It  is  the  site 
of  the  original  settlement  and  mission  established  by  the  Franciscan  monks,  and  the  old 
Mission  Church  still  stands  there  (PI.  XXIII,  B ),  as  the  fire  was  checked  at  this  point 
just  in  time  to  save  it. 


138 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


futile  until  late  on  Thursday  night,  after  a dynamite  expert  had 
been  put  in  charge.  A last  stand  was  made  in  the  western  part  of 
the  city,  at  the  broad  and  open  street,  Van  Ness  avenue.  Here  the 
dynamiters,  aided  by  the  shifting  of  the  wind  to  the  west,  were  able 
to  stay  the  progress  of  the  fire.  Everything  in  the  Mission  district 
had  been  burned,  except  at  places  where  the  flames  were  checked  by 
means  of  private  water  supplies.  Although  comparatively  feeble, 
the  fire  continued  in  some  parts  of  the  desolated  district  until  Satur- 
day morning,  April  22,  when  the  last  blaze  was  extinguished.  The 
wharves  and  a fringe  of  buildings  along  the  water  front  had  been 
saved  by  means  of  engines  and  State  fire  boats  drawing  water  from 
the  bay. 

The  area  of  the  burned  district-  (see  PI.  LYI)  is  4.05  square  miles, 
or  2,593  acres,  and  includes  490  blocks  entirely  burned  and  32  blocks 
partially  burned.  These  blocks  were  in  two  different  classes,  one 
being  the  “ 100-vara a block,”  and  the  other  the  “ 50-vara.”  Some 
structures  along  Mission  Creek  and  a few  residences  on  the  summits 
of  Telegraph,  Russian,  and  Clay  Street  hills  (PI.  LIV)  escaped. 
The  mint  and  a few  other  buildings  were  also  saved  by  means  of 
private  water  supplies. 

Thus  the  greatest  fire  in  the  history  of  the  world  destroyed  more 
than  4 square  miles  of  closely  built  city  property  estimated  at  $500,- 
000,000,  half  of  which  was  insured;  with  the  loss,  it  is  believed,  of 
about  800  human  lives  (though  the  official  count  is  less). 

San  Francisco  was  little  prepared  to  fight  a conflagration  under 
the  existing  conditions.  Ever  since  the  six  devastating  fires  of  the 
period  from  1849  to  1852  the  people  had  evidently  relied  on  the  excel- 
lence of  the  fire  department  (subsequently  organized),  the  damp 
atmosphere,  and  the  tradition  that  redwood,  which  composed  the 
exterior  of  90  per  cent  of  the  structures,  would  not  burn.  Dwellings 
were  not  protected  against  fire  either  from  within  or  without,  and  the 
same  may  be  said  of  most  of  the  boarding  houses  and  even  of  some  of 
the  public  hotels.  There  were  few  chemical  extinguishers,  private 
water  supplies,  or  other  fire  apparatus  in  existence.  In  the  congested 
business  district  buildings  that  had  ample  modern  means  of  fire  pre- 
vention within,  or  protection  against  fire  from  without,  were  the 
exception  rather  than  the  rule.  Few  buildings  had  metal  shutters, 
wire-glass  windows,  sprinkler  .systems  (interior  or  exterior),  or  pri- 
vate wells,  tanks,  or  pumps.  Some  buildings  where  these  preventives 
were  installed  were  saved,  although  surrounded  by  fire. 

Inflammable  wooden  buildings — remnants  of  the  pioneer  days  of 
1849 — were  scattered  through  the  business  districts  and  added  fuel 
to  the  flames.  The  magnificent  high  steel  structures  that  were  gutted 


° The  vara  is  the  Spanish  unit  of  length,  and  equals  33.38  inches. 


REPORT  OF  UNDERWRITERS’  COMMITTEE.  139 

by  the  fire  owe  their  desolation  for  the  most  part  to  their  environment 
by  these  inflammable  buildings. 

There  was  no  dynamiting  corps  in  the  fire  deparment  and  no  ade- 
quate salt-water  system  for  fighting  fires,  although  the  city  was 
almost  surrounded  by  salt  water,  and  there  were  no  fire  boats  be- 
longing to  the  department,  and  few  cisterns  in  the  streets  or  squares. 
Most  of  the  streets  were  very  narrow,  and  many  of  them  were  lined 
by  high  wooden  buildings.  With  the  water  mains  and  distribution 
system  incapacitated  by  the  earthquake,  it  is  no  wonder  that  the  city^ 
burned ; the  only  wonder  is  that  it  had  not  burned  before.  This  re- 
sult had  been  prophesied  by  insurance  inspectors  many  months 
previously. 

ABSTRACT  OF  REPORT  OF  ENGINEERS’  COMMITTEE  OF  THE 
NATIONAL  BOARD  OF  FIRE  UNDERWRITERS. 

The  Coast  Review,  an  insurance  paper,  gives  an  abstract  of  the 
report  and  conclusions  of  the  engineers’  committee  of  the  National 
Board  of  Fire  Underwriters.  This  report  was  published  in  October, 
1905,  many  months  preceding  the  occurrence  of  the  great  fire,  and  is 
epitomized  as  follows : 

The  area  of  San  Francisco  within  the  “fire  limits  ” was  1.6  square 
miles.  The  “ brick  district”  comprehended  0.95  square  mile,  and 
the  “ congested-value  district  ” 0.49  square  mile.  The  number  of  fires 
in  the  preceding  nine  years  was  moderate,  but  the  average  doss  at  each 
fire  was  two  or  three  times  the  loss  expected  in  cities  having  ordinary 
fire  protection.  The  water  supply  was  satisfactory  in  many  respects, 
although  the  pressure  (the  average  being  52  pounds)  was  too  low  for 
automatic  sprinkler  equipments,  standpipes,  etc.  The  fire  hydrants 
were  of  an  old  style,  and  many  water  mains  were  too  small.  There 
were  four  water  services,  varying  for  districts  of  different  levels.  It 
was  stated  that  the  fire  department  was  satisfactory  in  most  respects, 
but  that  the  building  laws  were  not  enforced  thoroughly  and  impar- 
tially. The  fire-alarm  system  was  criticised  adversely. 

The  “ congested-value  district  ” was  bounded  on  the  north  by  a 
mixed  mercantile,  warehouse,  and  dwelling  section ; on  the  west  by  a 
fashionable  boarding-house,  apartment,  and  residence  district;  on 
the  south  by  a compactly  built  mixed  district  composed  of  dwellings 
and  manufacturing  and  mercantile  buildings,  and  on  the  east  by  the 
Bay  of  San  Francisco.  This  district  consisted  of  101  blocks,  contain- 
ing 2,086  separate  buildings,  of  which  2.2  per  cent  were  fireproof, 
68.3  were  joisted  brick,  and  29.5  were  frame  buildings.  There  was 
only  one  sprinkler  equipment  in  the  district,  and  it  was  practically 
obsolete.  Premises  were  generally  clean  and  well  cared  for. 

The  “ potential  hazard  ” in  the  produce  and  commission  district 
bounded  by  Battery,  Washington,  Drumm,  and  Commercial  streets 
was  said  to  be  serious.  The  expert  inspectors  claimed  to  have  found 


140 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  EIRE. 


“ conflagration  breeders.”  In  regard  to  the  blocks  north  of  Market 
street  and  between  Powell  and  Taylor  streets  they  reported:  “This 
section  Contains  more  serious  exposures  and  conflagration  breeders 
than  any  other  equal  area  in  the  city.”  They  reported  “ frequent 
high  winds,”  the  absence  of  modern  protective  devices  generally,  the 
“ probability  feature  ” alarmingly  severe,  the  elements  of  a “ confla- 
gration hazard  ” present  to  a marked  degree,  and  the  topography 
unfavorable.  In  fact,  “ San  Francisco  has  violated  all  underwriting 
traditions  and  precedents  by  not  burning  up;  that  it  has  not  done 
so  is  largely  due  to  the  vigilance  of  the  fire  department,  which  can 
not  be  relied  upon  indefinitely  to  stave  off  the  inevitable.” 

This  report  was  locally  regarded  as  very  severe,  and  in  some 
respects — for  instance,  when  referring  to  winds,  redwood  lumber,  and 
hilly  topography  being  unfavorable — as  erroneous;  but,  unfortu- 
nately for  San  Francisco,  the  prophecy  has  come  true. 

EXTRACT  FROM  A SAN  FRANCISCO  FIRE  EXPERT’S  REPORT  TO  THE 
BRITISH  FIRE-PREVENTION  COMMITTEE. 

George  J.  Wellington,  who  was  born  and  reared  in  San  Francsico, 
and  therefore  can  not  be  accused  of  prejudice  against  that  city,  in 
his  report  to  the  British  fire-prevention  committee  of  London  in  1906, 
says,  among  other  things : 

A glance  at  the  city  from  a point  of  eminence  shortly  after  the  temblor 
had  subsided  at  once  disclosed  the  fact  that  San  Francisco  was  doomed.  Col- 
umns of  smoke  ascending  from  fires  at  many  different  points  made  apparent  a 
condition  that  no  fire  department  in  existence  could  cope  with,  on  account  of 
the  impossibility  of  assembling  sufficient  apparatus  at  each  fire  to.  control  it, 
and  particularly  on  account  of  the  fact  that  there  was  little  or  no  pressure  in 
the  hydrants.  . . . Observation  for  six  hours  from  the  top  of  a tall  office 
building  failed  to  illustrate  anything  not  already  known  to  fire  experts,  and 
previously  demonstrated  at  Baltimore  and  other  places.  Unprotected  openings 
of  brick  buildings,  improperly  hung  and  uncared-for  metal-clad  shutters,  inef- 
fective rolling  and  ordinary  iron  shutters,  were  conspicuous  by  their  weakness. 
Exposed  sides  of  hollow-tile  fireproofing  again  cracked  away ; concealed  piping 
again  forced  fireproofing  away  from  steel  members  that  it  was  intended  to  pro- 
tect; metal-lath  and  plaster  partitions  again  failed,  and  unprotected  steel  was 
warped  and  distorted,  permitting  floors  to  fall.  Tall  brick  buildings  with 
joisted  interiors  radiated  heat  to  wooden  cornices  and  window  frames,  which 
took  fire.  ...  In  fact,  everything  that  had  been  predicted  by  fire  engineers 
occurred. 

The  bigotry  of  architects,  the  cupidity  of  contractors,  and  the  penuriousness 
of  owners  have  laid  the  metropolis  of  the  Pacific  low.  The  work  of  intelligent 
architects  came  to  naught  against  the  creations  of  incompetent  ones.  The  own- 
ers of  well-constructed  buildings  were  burned  out  by  their  criminally  careless 
neighbors.  In  many  instances  talent  was  not  engaged  on  account  of  its  ability 
to  construct  permanently  and  well,  but  rather  for  its  shrewdness  in  erecting 
structures  that  would  earn  the  greatest  returns  for  sums  invested.  Competi- 


LAYOUT  OF  CITY  AND  CHARACTER  OF  BUILDINGS.  141 


tion  in  this  respect  has  led  to  the  use  of  inferior  materials  and  the  evasion  of 
building  laws  and  the  underwriters’  recommendations.  San  Francisco  possesses 
building  laws  in  plenty,  which  require  enforcement  rather  than  alteration.  A 
valuable  addition  to  present  ordinances  would  be  one  similar  to  that  in  force  in 
some  European  countries,  which  penalizes  owners  for  fires  that  escape  from  their 
buildings,  affording  protection  to  men  disposed  to  build  well. 

EFFECT  OF  THE  LAYOUT  OF  THE  CITY  AND  THE  CHARACTER  OF 

THE  BUILDINGS. 

San  Francisco,  as  already  stated,  is  divided  into  three  great  dis- 
tricts. Market  street,  the  great  artery  of  the  city,  120  feet  wide,  runs 
southwestward  from  the  bay,  and  divides  the  city  into  two  parts — 
first,  a level  district  on  the  south,  largely  filled  with  wooden  build- 
ings, factories,  foundries,  lodging  houses,  and  the  like,  but  around 
the  bay  extremity  of  the  street  covered  to  a considerable  extent  with 
buildings  of  brick,  stone,  or  steel  frame;  second,  the  uneven  and  in 
its  remoter  parts  hilly  district  on  the  north.  This  northerly  portion 
is  subdivided  by  Van  Ness  avenue,  which  separates  the  older  resi-. 
dence  district  from  the  newer  one  on  the  west. 

In  the  older  section  of  the  city,  between  Market  street  and  Van 
Ness  avenue,  the  streets  had  been  established  under  the  old  Spanish 
system  of  “ 100- vara  lots,”  as  they  are  locally  known,  each  block 
containing  about  76,000  square  feet.  West  of  Van  Ness  avenue  and 
south  of  Market  street,  in  parts  of  the  city  more  recently  surveyed 
and  built  upon,  the  blocks  are  much  larger,  and — particularly  along 
Market,  Mission,  and  adjacent  streets  to  the  south — were  built  up 
with  very  long  rows  of  buildings,  many  of  them  continuous  for 
hundreds  of  feet.  These  blocks  were  so  large  that  it  was  found 
necessary,  or  at  least  convenient,  to  subdivide  many  of  them  by  nar- 
row streets  or  alleys  that  permitted  the  ingress  and  egress  of  carts 
and  drays.  It  was  easy  for  the  flames  to  pass  across  these  narrow 
streets,  and  the  heat  was  in  many  places  so  great  that  buildings  on 
the  opposite  side  of  the  street  were  ignited  by  the  heated  air  without 
the  passage  of  any  flames. 

More  than  90  per  cent  of  the  buildings  in  San  Francisco  were  of 
wooden-frame  construction,  and  many  of  the  new,  modern,  and  so- 
called  u fireproof  ” buildings  were  surrounded  by  frame  structures 
of  an  old  type,  and,  of  course,  were  injured  or  destroyed*  by  their 
combustion.  The  fire  limits  permitted  these  wooden  structures  to 
approach  rather  close  to  the  business  section;  and  in  the  congested 
business  district  at  least  30  per  cent  of  the  buildings  were  of  frame 
construction,  some  of  them  four  or  five  stories  in  height.  Outside 
of  the  congested  district  many  business  houses  and  almost  all  dwell- 
ings were  frame  structures,  and  except  in  the  outskirts  of  the  city 


142 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  EIRE. 


were  closely  built  in  long  rows  extending  over  entire  blocks.  In  the 
business  district  almost  every  separate  structure  was  close  to  its 
neighbors.  Wide,  uncovered  spaces  separating  buildings  were,  as  a 
rule,  confined  to  the  outlying  suburbs.  In  the  compactly  built  dis- 
trict of  wooden  structures  a house  every  three  minutes  was  fre- 
quently the  rate  of  destruction  from  the  fire  during  the  high  wind 
that  prevailed  at  times. 

In  the  congested  business  district  about  75  per  cent  of  the  streets 
were  60  feet  wide,  and  a few  (about  30  per  cent)  were  at  least  80 
feet  wide.  These  streets  offered  very  little  obstruction  to  the  passage 
of  the  flames  or  heated  air,  and  it  was  aided  by  the  winds  that  were 
caused  largely  by  the  conflagration. 

The  height  limit  as  established  by  the  city  ordinances  was  220  feet 
for  buildings  of  class  A,  100  feet  for  class  B,  82  feet  for  class  C, 
and  45  feet  for  frame  buildings.  Brick  buildings  with  wooden  joists 
were  therefore  allowed  to  be  built  to  a height  of  eight  stories  if 
furnished  with  wire-lath  and  plaster  ceilings,  thus  affording  the  fire 
admirable  opportunities  for  destruction. 

BEHAVIOR  OF  STRUCTURAL  STEEL  AND  STEEL-FRAME 

BUILDINGS  SUBJECTED  TO  THE  EARTHQUAKE  AND 

FIRE. 

EFFECTS  DUE  PRIMARILY  TO  THE  EARTHQUAKE. 

INTRODUCTION. 

Structural  steel  as  a building  material  and  as  a principal  stress 
resistant  in  high  steel-frame  buildings  has  greatly  increased  in  favor 
since  its  entirely  satisfactory  behavior  in  the  recent  great  vibrations 
in  California ; for  while  it  possessed  strength  and  stiffness  to  a satis- 
factory degree,  it  also  displayed  an  amount  of  elasticity  that  avoided 
much  shearing  and  fracture,  even  under  the  vibrations  of  the  tallest 
steel- frame  structures. 

The  behavior  of  structures  of  the  various  types  in  San  Francisco 
and  elsewhere  in  the  area  destructively  affected  by  the  earthquake 
was  in  strict  accordance  with  the  merits  of  their  ‘foundations,  design, 
materials,  and  workmanship.  The  so-called  fireproof  buildings 
within  the  area  most  affected  by  the  earthquake,  and  afterwards,  in 
San  Francisco,  burned  over,  did  not  exceed  60  in  number.  Among 
these  buildings  were  8 having  steel  frames  and  hollow-tile  floor 
arches,  29  or  30  having  steel  frames  with  reenforced-concrete  floor 
arches,  and  2 having  reenforced-concrete  frames — one  of  these  of 
imperfect  design.  There  were  6 unfinished  buildings  with  steel 
frames,  and  10  having  brick  walls  and  fireproof  floor  arches. 


STRUCTURAL  STEEL  AND  STEEL-FRAME  BUILDINGS.  143 


FOUNDATIONS. 

It  is  believed  that  every  building  whose  foundations  were  well  and 
strongly  established — upon  deep  piling,  as  the  Union  Ferry  Building 
and  the  Merchants’  Exchange;  with  reenforced-concrete  slab,  as  the 
Call  Building ; upon  separate  concrete  piers  or  grillages  resting  upon 
good  beds  having  a uniform  load  per  square  foot,  as  the  Union  Sav- 
ings Bank  in  Oakland;  or  upon  any  other  type  of  excellent  founda- 
tion— escaped  injury  by  the  earthquake  to  the  foundations  themselves, 
nor  did  the  superstructure  owe  any  damage  to  inefficiency  in  those 
foundations. 

The  central  portion  of  California  was  subjected  to  a severe  earth- 
quake in  1868,  and  has,  on  a number  of  occasions  since,  been  slightly 
shaken  by  earthquake  shocks,  but  many  architects  and  engineers,  and 
the  people  generally,  had  become  so  accustomed  to  these  slight  move- 
ments of  the  earth’s  crust  that  little  attention  was  paid  to  them,  and, 
so  far  as  the  writer  can  learn,  architects  had  believed  that  in  estab- 
lishing solid  foundations  for  high  steel  buildings,  with  good  anchor- 
age and  bracing,  adequate  to  take  care  of  extreme  wind  force,  they 
had  sufficiently  guarded  against  the  effects  of  any  earthquake  vibra- 
tions which  might  occur.  As  a matter  of  fact,  the  provisions  thus 
made  seem  to  have  been  ample  and  safe  so  far  as  any  disturbance  of 
the  foundations  or  any  lack  of  support  of  the  superstructure  has 
been  detected.  Notwithstanding  the  severe  vibrations  these  tall 
buildings  have  been  called  upon  to  endure,  they  have  remained  plumb 
and  very  slightly  damaged  by  the  earthquake. 

STRUCTURAL- STEEL  FRAMES  EXPOSED  TO  VIBRATORY  MOTION. 

As  stated  by  A.  O.  Leuschner,  secretary  of  the  California  earth- 
quake commission,  and  also  by  Professor  Omori,  the  distinguished 
seismologist  of  Japan,  the  vibratory  motion  in  Berkeley  and  in  San 
Francisco  was  approximately  3 inches  in  a horizontal  direction  and 
about  1 inch  vertically,  the  time  of  the  first  oscillation  being  one  sec- 
ond. This  is  understood  to  be  the  vibration  on  very  hard  soil  or 
solid  rock.  Where  the  soil  was  softer  and  less  coherent  the  waves 
became  longer  and  the  movement  slower. 

This  vibratory  motion  had  a tendency  to  move  the  foundation  of 
a high  building  and  the  basement  immediately  in  connection  with 
it  forward  and  back,  and  perhaps  to  move  some  of  its  columns  in 
opposite  directions,  although  this  is  not  certain.  At  any  rate,  it 
apparently  had  the  effect,  owing  to  the  inertia  of  the  mass  of  the 
upper  part  of  the  building,  of  bringing  a maximum  bending  moment 
to  bear  on  the  frame  at  some  point  between  the  basement  and  the  top 


144 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


of  the  building — to  speak  roughly,  somewhere  near  the  middle  sto- 
ries. It  also  seemed  to  have  the  effect  of  producing  a horizontal 
shearing  stress  in  the  frame,  particularly  above  and  near  the  base- 
ment. The  frames  in  these  high  buildings  seemed  to  be  the  most 
severely  wrenched,  and  the  exterior  .walls,  stairways,  linings,  etc., 
most  injuriously  cracked  in  these  middle  stories.  For  example,  the 
magnificent  eighteen-story  Call  Building  seemed  to  be  well  braced 
against  bending  moment  and  shear,  but  the  eyebars  from  the  tenth 
to  the  sixteenth  floor  and  the  transverse  wind  bracing  are  reported 
to  be  somewhat  buckled,  the  maximum  occurring  on  the  thirteenth 
floor.  The  braces  were  warped  on  all  four  sides  of  the  building, 
and  there  was  also  probably  some  slight  distortion  of  the  steel  frame 
from  the  tenth  to  the  thirteenth  floors.  The  exterior  veneer  of  stone 
remained  practically  intact  up  to  the  tenth  floor,  above  which,  up 
to  the  sixteenth,  there  was  an  increasing  amount  of  damage,  some 
of  the  stone  being  considerably  out  of  place.  (See  also  p.  146.)  The 
same  thing  practically  can  be  said  of  the  new  Chronicle  Building, 
the  damage  to  the  stonework  of  which  can  be  noted  by  a close  inspec- 
tion of  PI.  XXX,  B.  The  earthquake  proved  the  absolute  neces- 
sity of  bracing  steel-frame  buildings  with  diagonal  braces,  so  far  as 
the  requirements  of  use  will  allow.  The  Mutual  Savings  Bank  and 
the  Shreve  and  Atlas  high  steel-frame  buildings  have  such  bracing 
and  remained  entirely  plumb  after  the  earthquake.  The  St.  Francis 
Hotel  and  the  Call  Building  were  somewhat  similarly  braced  and 
were  also  left  in  reasonably  good  condition. 

Some  architectural  authorities  assert  that  wind  bracing  put  in 
liberally  for  an  allowance  of  30  pounds  pressure  per  square  foot  will 
amply  care  for  earthquake  vibrations  of  an  intensity  equal  to  those  of 
April  18,  1906.  Undoubtedly  many  of  the  high  steel  buildings  in 
San  Francisco  were  designed  without  reference  to  earthquakes,  but 
they  have  nobly  withstood  their  effects,  and  steel  frames  have  proved 
themselves  entirely  adapted  to  earthquake  countries.  A careful  in- 
spection of  the  high  steel  frames  in  San  Francisco  shows  that  they 
suffered  comparatively  little  injury,  and  that  this  injury  was  con- 
fined to  the  shearing  of  rivets  and  connections,  particularly  in  the 
lower  stories  and  on  the  ground  floors,  and  to  some  buckling  of 
braces. 

After  the  earthquake,  bolts  and  rivets  in  the  Union  Trust  Building 
were  found  to  be  loose,  and  some  were  sheared  off.  This  damage  was 
due  apparently  to  faulty  construction,  careless  workmanship,  and  the 
insertion  of  field  bolts,  in  some  places,  instead  of  rivets.  It  was 
shown  that  the  rivets,  connection  joints,  etc.,  in  these  steel-frame 
structures  are  of  vital  importance,  and  that  in  order  to  resist  earth- 
quake vibrations  they  should  be  made  as  strong  and  effective  as  pos- 
sible, particularly  at  the  basement  and  first  floor. 


STRUCTURAL  STEEL  AND  STEEL-FRAME  BUILDINGS.  145 


MASONRY  WALLS  AND  STONEWORK. 

The  stone  exteriors  of  all  the  high  steel-frame  buildings  were  to 
a greater  or  less  extent  cracked  or  injured  under  the  action  of  the 
earthquake.  In  some  places,  owing  probably  to  imperfect  bond  be- 
tween the  veneer  and  the  steel  frame,  the  stone  veneer  was  displaced 
and  the  walls  were  bulged  outward;  in  others,  blocks  were  thrown 
to  the  ground  and  bricks  or  arch  stones  from  windows  and  other 
exterior  openings  were  dropped  out  of  place.  This  disintegrating 
effect  had  its  maximum  in  the  intermediate  stories  between  the  top 
and  the  base'  of  the  building,  a very  good  example  being  the  Union 
Savings  Bank  in  Oakland.  This  eleven-story  steel- frame,  stone- 
veneer  structure  gave  opportunity  for  careful  and  comprehensive 
study  of  earthquake  effects  independently  of  fire,  since  it  is  really 
the  only  high  steel-frame  structure  in  the  disturbed  area  which  was 
not  subjected  to  fire.  In  this  building  the  steel  frame  is  intact  and 
uninjured,  so  far  as  can  be  ascertained.  The  marble  veneer  along 
the  stairways  and  corridors  and  the  sandstone  exterior,  particularly 
in  the  fourth,  fifth,  sixth,  and  seventh  stories,  were  somewhat  cracked 
and  disturbed,  indicating  not  only  a bending  but  a shearing  action; 
and  the  brick  in  the  arches  in  some  of  the  windows  in  these  stories 
have  dropped  to  the  ground.  Otherwise  the  building  escaped  dam- 
age, and  it  has  been  continuously  in  use  since  the  earthquake. 

The  Aronson  Building,  at  Third  and  Mission  streets,  had  stone 
piers  running  from  the  bed  up  to  the  street  level.  These  were  badly 
wrenched  and  cracked  by  sheer  action,  and  in  the  ninth  story  two 
courses  of  stone  in  the  arches  above  the  soffit  course  were  badly 
cracked,  apparently  for  the  same  reason.  In  the  Call  Building, 
where  the  stonework  ends  at  the  sidewalk  level,  the  corner  piers  were 
not  found  to  be  cracked,  but  in  the  James  Flood  Building  (Pis. 
XXXIII,  B ; XXXV,  A) , where  the  stonework  extends  to  the  bottom 
of  the  basement,  the  corner  piers  were  cracked  by  earthquake  action. 

RELIABILITY  OF  STRUCTURAL  STEEL. 

Structural  steel  is  a very  reliable  material.  It  is  produced  and 
also  placed  in  position  by  high-class  skilled  labor  and  is  not  subject 
to  the  flaws  which  sometimes  appear  in  concrete  work  as  a result  of 
poor  quality  of  labor  and  inefficient  inspection.  Builders  in  this 
country  have  had  much  experience  in  the  use  of  structural  steel,  and 
feel  sure  of  what  it  will  do  and  for  what  it  stands.  It  is  no  longer 
in  the  experimental  stage  as  to  resistance  either  to  earthquake 
tremors  or,  when  properly  fireproofed,  to  conflagration.  Construc- 
tors in  San  Francisco  feel  that  this  material  has  safely  and  trium- 
phantly passed  through  a most  trying  ordeal. 


146 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


EFFECTS  OF  THE  FIRE. 

BUILDINGS. 

Structural  steel  in  the  steel-frame  buildings  subjected  to  the  ter- 
rific heat  of  the  great  conflagration  behaved  satisfactorily  wherever 
it  was  properly  and  amply  protected  by  any  method  adopted  for 
fireproofing.  In  no  instance  that  has  come  under  the  observation  of 
the  writer  has  the  steel  been  injured  or  deformed  where  such  fire- 
proofing was  of  the  proper  kind  and  remained  intact  after  the  earth- 
quake. Unfortunately,  in  many  places  there  was  practically  no  fire- 
proofing whatever,  or  it  was  very  poor  in  design  or  workmanship, 
or  both,  and  as  a consequence  failed  miserably.  Columns  were  soft- 
ened and  buckled.  Girders  were  softened  to  such  a degree  that  they 
sank  by  their  own  weight,  some  pulling  after  them  the  walls  into 
which  they  were  built,  others  falling  into  the  fiery  furnace  below, 
as  in  the  Cowed  Building  (PI.  LI,  B ),  where  the  fireproofing  either 
was  lacking  or  proved  defective  in  the  fire.  In  such  places  the  col- 
umns were  buckled  and  some  of  them  telescoped,  thus  removing  all 
support  for  the  floors  above.  In  other  buildings  where  the  fireproof- 
ing was  fairly  good  and  effective,  as  in  the  James  Flood  and  the 
Call  buildings,  the  structure  remained  ready  for  rehabilitation. 
Although  all  the  steel  girders  or  columns  that  were  subjected  to 
intense  heat  on  account  of  lack  of  fireproofing  did  not  fall,  yet  many 
of  them  were  rendered  unfit  for  further  use. 

Prominent  among  the  steel  structures  was  the  eighteen-story  Call 
Building,  with  dome  and  lantern,  the  architectural  pride  of  the 
city.  This  building  took  fire  through  a tunnel  leading  from  the 
power  house  in  the  rear  of  the  building,  across  Stevenson  street.  The 
fire  was  drawn  in  by  the  draft  up  the  18  stories  of  the  elevator  shaft, 
which  acted  like  an  enormous  chimney,  the  flames  being  sucked  up 
to  the  topmost  story  with  great  force  and  rapidity.  The  heat,  of 
course,  became  intense,  and  all  combustible  matter  on  the  interior 
of  the  building  was  quickly  consumed,  but  the  fireproofing,  although 
not  perfect  in  design  and  execution,  so  far  protected  the  steel  frame 
that  it  remained  only  slightly  damaged  and  ready  for  refitting.  The 
marble  lining  of  the  walls  and  corridors,  and  the  glass  in  the  exterior 
and  interior  windows,  were  all  destroyed,  and  the  metal  trimmings 
were  to  a considerable  extent  melted  or  ruined.  But  the  steel  frame 
and  stone  exterior,  with  the  exception  of  that  on  some  of  the  middle 
stories,  remains  little  injured,  and  parts  of  the  building  are  contin- 
uously in  use. 

In  the  same  way  the  James  Flood  Building,  one  of  the  newest  and 
largest  steel-frame  structures,  excellent  in  design  and  first-class  in 
workmanship,  was  fairly  well  fireproofed;  and  although  gutted  by 


STRUCTURAL  STEEL  AND  STEEL-FRAME  BUILDINGS.  147 


•the  fire,  it  is  being  rapidly  refitted  for  store  and  office  occupation. 
The  Western  Pacific  Bank  reoccupied  its  old  quarters  on  the  first 
floor  of  this  building  almost  immediately  after  the  fire. 

FIREPROOFING. 

GENERAL  CONDITIONS. 

It  can  be  truthfully  stated  that  perfect  fireproofing  of  buildings 
in  San  Francisco,  even  in  those  of  the  newest  and  most  modern 
type,  was  the  exception  and  not  the  rule.  The  bent  or  broken 
columns  and  the  distorted  or  disfigured  steel  girders  in  many  of 
the  burned  buildings  demonstrate  this  fact  (PI.  XXVII,  B). 
Wherever  structural-steel  framework  was  covered  with  fireproofing 
material  of  the  best  design,  executed  with  conscientious,  skillful 
workmanship,  the  steel  remained  uninjured  after  the  fire. 

The  lessons  taught  by  the  great  Chicago  and  Baltimore  fires  had 
been  applied  by  but  few  of  the  architects  of  San  Francisco,  on 
account  of  cost  restrictions  insisted  on  by  owners,  and  very  much 
of  the  damage  inflicted  on  these  high-class  structures  during  the 
conflagration  is  directly  traceable  to  the  imperfect  fireproofing  put 
in,  or  to  the  entire  absence  of  fireproofing.  Some  of  the  failures  were 
evidently  and  directly  attributable  to  poor  workmanship. 

CONCRETE. 

There  are  two  opposing  parties  in  the  matter  of  fireproofing  in 
San  Francisco — those  who  have  favored  the  hollow-tile  system, 
and  those  who  believe  in  concrete  as  the  best  fireproofing  material. 
The  Bekins  Van  and  Storage  Company’s  warehouse,  the  only  build- 
ing of  considerable  size  in  the  city  constructed  of  reenforced  con- 
crete, has  already  been  mentioned  as  resisting  the  action  of  the  earth- 
quake and  fire.  In  this  building  the  concrete  acted  as  a perfect 
fireproofing  protection  for  the  steel. 

Good  Portland-cement  concrete  has  won  a triumph  for  itself  in 
fireproofing  in  San  Francisco,  for  wherever  well  made  and  properly 
laid  upon  the  steel  girders  or  columns,  it  protected  the  metal.  In 
very  hot  fires  the  exterior  portions  were  disintegrated,  and  in  some 
places  the  whole  mass  was  cracked,  necessitating  removal,  but  the  fire- 
proofing it  furnished  during  the  conflagration  was  excellent.  Exami- 
nation showed  also  that  it  protected  well  against  rust.  The  heat  to 
which  it  was  subjected  was  very  great,  in  places  common  mortar 
being  fused  and  ironwork  in  walls  melted. 

The  steel  beams  and  girders  in  the  St.  Francis  Hotel,  the  Mer- 
chants’ Exchange,  the  Mutual  Savings  Bank,  and  other  similar 
structures  that  were  thoroughly  fireproofed  with  concrete  endured 
the  fire  exceedingly  well. 


148 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  EIRE. 


The  weight  of  Portland-cement  concrete  is  a drawback,  and, 
moreover,  concrete  is  expensive  when  well  made  and  applied.  Cinder 
concrete  was  well  esteemed  for  fireproofing  for  floors,  but  the  scarcity 
of  good  cinders  in  the  city  rendered  its  general  employment  imprac- 
ticable. 

TERRA  COTTA. 

As  fireproofing  for  floors  terra-cotta  tiling  has  not  given  universal 
satisfaction.  It  is  lighter  than  concrete,  but  the  wrenching  of  build- 
ings during  the  earthquake  opened  many  of  the  joints  and  the  mor- 
tar was  destroyed — as  in  the  Mills  Building,  a large  ten-story  steel- 
frame  structure  of  the  older  type,  having  self-supporting  walls.  The 
mortar  joints  in  the  tiling  were  started  by  the  earthquake,  and  the 
mortar  was  disintegrated  by  the  fire,  the  floors  being  destroyed  and 
the  lower  surfaces  of  the  tiling  badly  spalled.  The  same  effect  was 
noticeable  to  a certain  extent  in  the  excellent  Union  Trust,  Crocker, 
and  James  Flood  buildings.  In  the  last  named  the  flooring  was  fire- 
proofed with  terra-cotta  arched  tiles,  covered  with  concrete  on  top 
and  finished  beneath  by  an  efficient  ceiling  plastered  on  wire  lath. 
The  fireproofing  was  less  injured  in  this  building  than  in  almost 
any  other. 

Terra-cotta  fireproofing  of  columns  was  in  many  buildings  a fail- 
ure, not  so  much  on  account  of  the  nature  of  the  material  as  because 
of  its  insufficiency  in  quantity  and  poor  or  imperfect  method  of  appli- 
cation. Wooden  studs  were  in  many  places  put  behind  the  terra 
cotta.  These  burned  out  quickly,  leaving  the  material  unsupported. 
Pipes  and  wires  were  run  up  between  the  column  and  the  fireproof- 
ing, and  the  twisting  or  expansion  of  the  pipes  caused  by  the  earth- 
quake movement  broke  the  protecting  cover.  Imperfect  junctions 
with  ceilings  above  or  floors  beneath  were  common.  That  such  imper- 
fect construction  should  never  be  adopted  has  been  fully  demonstrated 
in  San  Francisco. 

Porous  terra  cotta  has  been  found  more  satisfactory  than  the  hard 
and  glazed  varieties.  For  inclosing  columns,  the  round  porous  forms 
have  proved  more  stable  and  efficient  than  the  rectangular  ones,  as 
shown  in  the  Spring  Valley  Water  Company’s  building  (PI.  XLV, 
A)  and  the  Aronson  Building  (PI.  XXVII,  B). 

PLASTER  AND  METAL  WORK. 

Common  plaster  on  wire  mesh,  metal  lath,  or  expanded  metal  was 
very  generally  used  for  the  fireproofing  of  columns,  partitions,  and 
the  like,  on  account  of  its  cheapness,  but  was  a failure  when  subjected 
to  a hot  fire,  as  proved  in  the  Hotel  Fairmount  (PI.  XXXIV),  the 
Hotel  Hamilton,  and  several  other  buildings.  This  failure  was  much 
more  noticeable  where  only  a single  wrapping  or  thickness  of  the  wire 


STRUCTURAL  STEEL  AND  STEEL-FRAME  BUILDINGS.  149 

mesh,  etc.,  was  used  than  with  the  double  wrapping.  But  even  the 
latter  proved  to  be  too  weak  and  disintegrable  to  pass  successfully 
through  a severe  earthquake  or  a fire  and  a strong  stream  of  water 
from  a fire  hose.  The  plaster  quickly  cracks  and  falls  away  from  the 
metal.  No  doubt  these  materials  will  be  used  in  the  future  by  owners 
demanding  cheapness  of  construction,  but  they  will  satisfy  the 
requirements  only  in  cases  of  mild  exposure.  Good  gravel  concrete 
in  place  of  the  plaster,  if  of  considerable  thickness,  has  been  found  to 
give  better  results. 

The  failure  of  the  plaster  and  metal  method  and  some  other  meth- 
ods of  fireproofing  in  San  Francisco  is  directly  traceable  to  the 
commands  of  owners  to  their  architects  to  cheapen  as  far  as  practi- 
cable the  fireproofing  and  the  construction  generally,  in  order  to 
receive  greater  interest  on  their  investments.  Much  of  this  cheapen- 
ing has  been  done  in  spite  of  the  protests  of  the  designer,  and  it  is 
in  an  entirely  wrong  direction;  for  rates  of  insurance  are  largely 
reduced  with  improvements  in  fireproofing,  and  as  the  cost  of  the 
steel  frame  and  its  proper  fireproofing  seldom  exceeds  27  per  cent 
of  the  cost  of  the  building,  it  seems  wise  to  protect  the  other  73 
per  cent  with  adequate  materials. 

brickwork. 

In  some  buildings  in  San  Francisco,  brick  laid  in  rich  Portland- 
cement  mortar  has  been  found  to  be  an  excellent  fireproof  covering; 
but  it  is  objectionable  on  account  of  the  bulkiness  of  the  brick  and 
the  rusting  of  the  steel,  as  in  basement  stories.  Good  brick  withstood 
the  severe  fire  well,  and  where  laid  in  rich  cement  afforded  a strong 
fireproof  wall  or  pier.  At  least  4 inches  of  brickwork  was  found 
necessary,  and  a layer  of  concrete  3 inches  in  thickness  between  that 
and  the  steel  was  a great  improvement  and  served  well  to  protect 
the  steel  from  rust.  But  this  method  will  probably  not  be  followed 
in  general,  on  account  of  weight,  bulk,  and  expense.  Hollow  brick 
and  tiling  were  efficient  also  when  properly  and  liberally  used,  porous 
tiles  proving  to  be  the  better. 

The  well-known  Palace  Hotel  was  built  about  thirty  years  ago, 
a few  years  after  the  earthquake  of  1868,  and  before  the  introduction 
of  steel- frame  structures  and  concrete  steel.  It  was  intended  to  be 
earthquake  proof  as  well  as  fireproof,  and  was  built  with  very  heavy 
walls  of  brick,  most  of  them  being  2 feet  or  more  in  thickness,  laid 
in  cement  mortar,  and  strongly  braced  by  many  cross  and  partition 
walls.  In  the  brickwork,  at  every  3 or  4 feet  in  height,  were  laid 
bands  of  iron,  riveted  together  at  their  ends  and  crossings.  This 
building,  although  of  the  old  type,  successfully  endured  the  great 
earthquake,  its  walls  being  practically  uninjured  (Pb  XXX?  B)  ; 

7171— Bull.  324—07 -11 


150 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


and  although  gutted  by  the  fire,  which  gained  access  through  the 
unprotected  windows  and  wooden  casings,  was  so  strong  on  its 
foundations  that  very  vigorous  blasting  operations  were  required  to 
throw  down  its  walls. 

REEKFORCED  CONCRETE. 

There  was  in  San  Francisco  at  the  time  of  the  earthquake  only  one 
building  of  considerable  size  constructed  of  reenforced  concrete. 
This  fact  was  due  to  the  opposition  of  certain  labor  unions  to  the  use 
of  this  material  in  place  of  brick  and  stone. 

The  building  referred  to  is  that  of  the  Bekins  Van  and  Storage 
Company,  at  190  West  Mission  street  (PI.  XXVII,  A).  This  build- 
ing had  outside  walls  of  brick,  but  was  massively  constructed  on  the 
interior  with  columns,  beams,  and  floors  of  reenforced  concrete.  It 
was  originally  intended  to  carry  it  to  a height  of  four  stories,  but  on 
account  of  the  earthquake,  which  occurred  during  construction,  the 
building  was  finished  to  include  only  the  second  story.  At  tht  time 
of  the  fire  the  permanent  doors  of  iron  were  not  in  place,  and  the 
fire  gained  access  to  the  front  or  south  room,  where  very  slight  dam- 
age was  inflicted.  The  entire  main  interior  and  the  goods  stored 
therein  were  unharmed,  and  the  building  has  been  in  continuous 
use  since  completion.  The  brick  building  adjoining,  however,  was 
badly  injured  by  the  earthquake  and  was  afterwards  burned. 

LESSONS  FROM  THE  VARIOUS  TYPES  OF  BUILDINGS. 

Great  destructive  earthquakes  have  seldom  occurred  twice  in  the 
same  locality  during  centuries  of  time,  but,  so  far  as  man  knows,  one 
may  occur  at  any  time  anywhere  on  the  earth’s  surface.  On  the 
other  hand,  destructive  conflagrations  in  cities  have  happened  many 
times,  but  most  of  them  might  have  been  avoided  by  wise  and  ade- 
quate provision  for  fire  prevention,  protection,  and  extinguishment. 

In  San  Francisco  the  earthquake  could  not  haA^e  been  averted,  but 
its  disastrous  effects  on  structures  could  have  been  prevented  by  the 
use  of  proper  materials  correctly  applied  in  the  execution  of  skillful 
and  scientific  designs,  carried  out  by  good  conscientious  workmen 
under  honest  and  able  supervision.  The  city’s  official  inspection  has 
usually  been  very  inefficient. 

The  buildings  in  California  that  were  ruined  or  badly  injured  by 
the  last  earthquake  may  be  divided  into  four  classes : 

The  first  class  comprises  buildings  of  a public  character,  such  as 
city  halls  (PL  XXXI),  court-houses  (PL  XXXIX,  A ),  asylums, 
public  schoolhouses,  etc.,  which  Avere  badly  desibned  and  constructed 
or  for  the  construction  of  which  insufficient  funds  had  been  voted,  so 
that  the  materials  and  workmanship,  under  imperfect  inspection,  or 


LESSONS  FROM  THE  VARIOUS  TYPES  OF  BUILDINGS.  151 


worse,  were  of  very  poor  quality.  In  contrast  to  such  construction 
were  the  United  States  Government  buildings — the  mint  and  the 
appraisers’  (or  customs)  building  (PI.  XXVIII,  X),  in  San  Fran- 
cisco, and  the  post-office  building  in  Oakland — all  of  which  were 
either  entirely  uninjured  or  very  slightly  injured  by  the  earthquake. 
These  buildings  were  well  designed  and  constructed  with  the  best 
materials  and  workmanship,  upon  foundations  that  had  been  tested 
and  found  strong  and  satisfactory.  The  results  to  both  of  these 
classes  of  buildings  were  fully  to  be  expected. 

As  a second  class  of  buildings  that  suffered  badly  may  be  grouped 
those  of  the  oldest  type  of  wooden  structure  in  San  Francisco,  lightly 
resting  upon  slim  wooden  underpinning,  which  stood  upon  soft  and 
unstable  soil  or  loose,  unconsolidated  sand.  Such  houses  went  down 
at  the  first  shock,  as  one  would  naturally  expect.  In  contrast  to  these 
flimsy  structures  are  the  thousands  of  more  substantially  constructed 
wooden  buildings  that  still  stand  intact,  except  as  to  chimneys  and 
some  plastering,  all  over  the  unburned  part  of  the  city.  These 
structures  were  built  fairly  well  and  upon  stable  foundations;  and 
the  writer  believes  from  his  personal  observation  that  no  well- 
founded  and  well-constructed  building  of  wood  in  San  Francisco 
was  injured  to  a greater  degree  than  those  just  mentioned.  In  a 
country  subject  to  earthquakes  a strongly  framed  and  well-founded 
wooden  house,  not  exceeding  three  stories  in  height,  with  nondisin- 
tegrating plaster  and  finish,  light  tile  chimneys,  and  ample  fire  pre- 
vention and  protection,  would  seem  to  be  the  ideal  type  of  residence 
structure. 

Experience  shows  that  buildings  constructed  with  exterior  brick 
walls  laid  in  common  mortar,  with  timber  columns  and  girders,  tied 
and  braced  little  or  not  at  all,  constitute  a third  class  of  buildings 
which  are  nonresistant  to  a severe  earthquake,  particularly  if  they 
are  erected  upon  a poor  foundation.  Even  if  the  girders  and  columns 
are  of  metal,  they  are  pulled  apart,  and  the  walls  fall  inward  or  out- 
ward during  the  shock.  Only  rich  Portland  cement,  laid  with  wetted 
brick,  and  strong  joists,  ties,  and  anchorage,  endured  the  stress. 

The  behavior  of  the  high  steel-frame  office  buildings,  which  con- 
stitute the  fourth  class,  has  shown  that  in  order  to  resist  perfectly 
the  bending  moments  and  shears  induced  by  the  swaying  due  to  the 
earthquake  movement,  such  buildings  should  be  stiffened  in  their 
joints  and  connections  by  the  best  riveting  combinations,  and  knee  and 
other  bracing,  particularly  at  or  near  the  ground  floor.  This  require- 
ment is  of  the  utmost  importance,  and  so  also  is  the  one  that  the  sway- 
ing referred  to  should  be  diminished  by  the  liberal  introduction  of 
diagonal  and  wind  bracing  throughout.  The  proper  bracing  in  the 
lower  stories  has  in  some  buildings  been  omitted,  on  the  demand  of 


152 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


owner  or  lessee,  to  afford  more  glass  or  light  space,  but  such  design 
has  a weakening  effect,  and  should  be  discouraged.  The  Marston 
Building,  on  Kearney  street,  is  an  object  lesson  in  this  respect.  On 
the  other  hand,  the  Whittell  Building,  on  Geary  street,  near  Union 
square,  is  commended  for  its  deep  plate  girders  and  heavy  steel 
generally.  It  stood  well,  and  no  rivets  were  sheared.  Columns, 
exterior  and  interior,  in  steel-frame  buildings,  should  in  future  be 
put  in  more  liberally  on  the  first  and  second  stories,  and  the  strongest 
joints  and  connections  should  be  adopted  in  order  to  resist  the  bend- 
ing and  shearing.  These  improvements  will  greatly  stiffen  the  steel 
frame,  and  prevent  the  cracking  of  the  walls.  The  Kohl  Building, 
thus  stiffened  by  lattice  girders  on  all  floors,  was  uninjured  in  its 
exterior  stonework  and  brickwork,  although  built  upon  the  edge  of  the 
made  ground  along  the  old  shore  line.  With  such  strengthening  the 
high  steel  structures  will  safely  endure  an  earthquake  of  even  greater 
severity  than  that  of  April  18,  1906.  This  kind  of  building  has 
proved  its  worth  and  reliability,  and  minor  improvements,  as  advo- 
cated, will  produce  an  enduring  structure. 

In  a fifth  class  are  to  be  placed,  but  not  as  failures,  concrete  and 
reenforced-concrete  structures.  These  have  become  popular  with  a 
large  number  of  designers  in  San  Francisco,  on  account  of  the 
strength  claimed  for  them,  and  on  account  of  the  indestructibility, 
facility  of  construction,  and  fire  and  rust  protection  that  their 
materials  afford.  Unfortunately  for  San  Francisco,  there  were  very 
few  structures  of  concrete  or  reenforced  concrete  in  the  city  at  the  time 
of  her  great  trial ; but  these  few  behaved  well  during  both  the  earth- 
quake and  the  resulting  fire.  Therefore,  although  such  structures 
are  admittedly  new  and  comparatively  experimental  on  the  Pacific 
coast,  the  confidence  reposed  in  them  has  already  led  to  the  designing 
and  construction  of  a number  of  large  buildings  of  this  type  for 
public  or  business  purposes.  At  present  the  sentiment  is  to  limit 
them  to  a height  of  six  or  eight  stories,  on  account  of  their  experi- 
mental character  and  because  of  the  fear  that  greater  height  would 
permit  a reversal  of  stress,  due  to  earthquake  and  wind  force  in  their 
reenforced  girders.  It  is  agreed  that  the  columns  should  be  reen- 
forced with  steel  and  braced  together  wherever  possible;  that  the 
girders  should  be  similarly  reenforced  for  tension  and  shear,  and  jj 
made,  so  far  as  practicable,  continuous  over  the  columns;  and  also 
that  the  joints  and  connections  should  be  strongly  stiffened  and  the 
curtain  walls  strengthened  by  a reenforcement. 

Mill  construction  with  brick  will  undoubtedly  be  utilized  in  many 
buildings  for  a considerable  time  to  come,  but  the  lesson  has  been 
taught  that  the  materials  used  should  be  first-class  pressed  brick,  well 
wetted,  and  cement  mortar,  and  that  all  parts  should  be  thoroughly 


FIRE-FIGHTING  APPARATUS. 


153 


tied  and  anchored  together.  San  Francisco’s  experience  has  proved 
that  this  rule  is  a most  important  one  to  follow  in  all  brick  and  stone 
construction,  and  its  neglect  in  the  past  has  resulted  in  much  loss  and 
ruin. 

FIRE-FIGHTING  APPARATUS  AND  FIRE-RESISTING 

MATERIALS. 

The  damage  inflicted  on  San  Francisco  from  the  direct  and  imme- 
diate effects  of  the  earthquake  was  relatively  small,  being  estimated 
at  only  3 to  10  per  cent  of  the  total  loss ; but  a subsequent  and  indirect 
effect  was  to  paralyze  the  water  supply  and  its  distributing  system, 
start  a great  conflagration  and  render  impossible  its  extinguishment 
with  the  means  at  hand,  cause  the  death  of  at  least  600  human  beings, 
burn  approximately  $500,000,000  worth  of  property,  render  home- 
less and  miserable  200,000  people,  and  inflict  remoter  damages  to 
business,  commerce,  and  labor,  only  to  be  estimated  in  the  future. 
Inasmuch  as  it  can  be  plainly  seen,  by  looking  backward,  that  nearly 
all  of  this  destruction  and  suffering  might  have  been  prevented  by 
wise  foresight  and  provision,  it  is  felt  that  a warning  should  be  sent 
to  all  the  cities  in  the  world.  Any  city  that  disregards  this  warning 
will  be  guilty  of  a great  crime. 

San  Francisco  should  have  had  separate  and  ample  water  mains 
entering  the  city  on  several  independent  lines  from  different  sources 
of  supply,  and  numerous  distributing  reservoirs  on  the  hills  in  vari- 
ous parts  of  the  city,  always  well  filled,  independent  and  yet  with  a 
distributing  system  meshing  the  entire  area,  with  its  pipes  so  joined 
or  valved  that  they  could  be  separated  or  united  as  desired.  There 
should  have  been  in  that  city,  almost  surrounded  by  salt  water,  a 
separate  system  of  flexible  salt-water  mains  for  fire  and  sewer  pur- 
poses, and  numerous  large  cisterns  in  her  streets,  laid  in  reenforced 
concrete,  with  somewhat  flexible  lining  and  pipes.  These  cisterns, 
only  a few  blocks  apart,  should  have  been  filled  at  all  times  with  salt 
water.  There  should  have  been  many  wide  streets — like  Van  Ness 
avenue,  where  the  fire  was  finally  checked — and  many  large  squares, 
the  city  being  thus  divided  into  numerous  fire  districts.  The  fire 
department  should  have  included  a dynamiting  corps  of  experienced 
fire  fighters,  and  a number  of  fire  boats  always  ready  along  the  water 
! front  and  among  the  shipping.  None  of  these  things  did  San  Fran- 
j|  cisco  have.  With  these  means  available,  probably  this  story  of  the 
greatest  fire  in  history  would  never  have  been  written. 

Of  a building’s  entire  fire  risk,  that  from  fire  within  the  building 
is  estimated,  on  the  average,  at  40  per  cent,  the  other  60  per  cent  of 
the  risk  being  from  exterior  fires.  This  risk  for  interior  fires  should 


154  THE  SAN  FRANCISCO  EARTHQUAKE  AND  EIRE. 

be  reduced  to  a minimum  by  ample  provision  for  fire  prevention. 
As  far  as  practicable,  combustible  material  should  be  eliminated. 
Several  of  the  fine  so-called  fireproof  buildings  in  San  Francisco  were 
injured  chiefly  by  the  burning  of  their  wooden  trim,  floors,  doors, 
office  furniture,  papers,  books,  carpets,  rugs,  etc.  Wooden  floors  have 
proved  to  be  dangerous  and  objectionable;  but  in  some  places  non- 
combustible wood  may  be  used  for  them  and  for  the  interior  trim, 
as,  for  example,  where  the  heat  could  never  be  very  great.  Metal 
trim,  doors,  windows,  sash,  and  casings,  together  with  plate  glass,  or, 
better,  wire  glass,  may  confine  a fire  to  a single  room,  preventing  a 
general  combustion.  Adequate  fire-extinguishing  apparatus — such  as 
fire  hose,  always  connected  with  good  water  pressure,  wells  with  auto- 
matic pumps,  and  tanks  in  the  basement  or  upon  the  roof,  with  pipe 
connections — was  lacking  in  nearly  all  of  San  Francisco’s  buildings, 
even  in  those  of  the  highest  class.  In  the  California  Electric  Com- 
pany’s building  the  standpipes,  with  attached  hose,  the  well,  pump,  1 
and  tank  in  the  basement,  and  the  roof  tank,  together  with  the  metal 
sash  and  the  wire-glass  windows,  proved  the  value  of  such  a private 
system,  saving  that  property  from  the  hot  fire  around  it,  though 
every  adjacent  structure  was  burned.  As  this  building  was  not  fire- 
proof, the  value  of  the  fire-extinguishing  system  can  be  well  under- 
stood, and  had  all  the  large  establishments  been  equally  well  equipped 
the  conflagration  would  have  been  quickly  checked  and  a vast  amount  ; 
of  property  saved.  Automatic  sprinklers  connected  with  the  above-  • 
mentioned  plant  will  afford  excellent  fire  protection  within  and  will 
greatly  reduce  insurance  rates. 

While  the  fire  danger  from  exterior  fires  to  a given  building  is 
ordinarily  estimated  at  60  per  cent,  this  risk  practically  becomes  100 
per  cent,  of.  course,  in  a great  conflagration.  In  San  Francisco  little 
protection  from  exterior  fires  had  been  adopted.  There  were  few 
metal  shutters  or  steel  roller  shutters,  and  most  of  those  were  of 
imperfect  design,  proving  unsatisfactory  when  tested.  The  open- 
ings in  walls  were  fatal  points  of  weakness  in  all  the  great  buildings. 
Wire-glass  windows,  though  few  in  number,  behaved  well,  but 
wooden  instead  of  metal  sashes  were  great  sources  of  fiery  contagion. 
Metal  covering  over  wooden  doors  and  window  frames  was  generally 
inefficient.  Ordinary  glass  was  quickly  cracked  by  heat  from  the 
exterior;  the  sashes  took  fire  and  the  flames  rushed  in  through  the 
openings,  consuming  all  combustible  material  within.  Many  of  the 
best  buildings  were  gutted  in  this  manner.  Had  they  been  furnished 
with  metallic  shutters  of  the  best  design,  with  wire  glass  in  metal 
sashes,  and  with  cornice  and  other  exterior  sprinklers,  supplied  by  a 
private  water  plant,  they  certainly  might  have  been  saved.  Thus 
the  employees  of  the  United  States  mint  (PI.  XXXVIII),  with  a 


FIRE-RESISTING  MATERIALS.  155 

scanty  private  supply  of  water,  made  a desperate  and  gallant  fight 
from  the  roof  of  the  building  and  within,  and  saved  it,  little  injured. 

As  most  metallic  shutters  rapidly  deteriorate  with  time,  rust,  and 
weather,  and  often  become  jammed  so  that  they  will  not  close,  many 
architects  prefer  wire  glass  in  hollow  metallic  sash  and  window 
sprinklers.  This  combination  has  proved  effective. 

San  Francisco’s  experience  indicates  that  wells  and  elevator  shafts, 
running  up  through  many  stories,  should  be  guarded  by  brick  or 
reenforced-concrete  walls,  fitted  with  double  metal  rolling  doors, 
bolted  to  the  walls  to  allow  for  expansion,  or  with  automatic  sliding 
doors  and  wire-glass  partitions.  There  was  little  or  no  provision 
for  cutting  off  the  draft  of  air  that  will  ascend  through  such  a shaft 
during  a fire,  and  great  destruction  resulted  in  consequence.  The 
Call  Building  took  fire  from  the  power  house  behind  it,  on  the  other 
side  of  Stevenson  street,  the  heat  being  drawn  through  the  tunnel  to 
the  elevator  shaft,  up  which  it  rushed  with  the  fierce  draft  given  by 
the  18  stories,  breaking  glass  and  burning  doors,  furniture,  trim- 
mings, and  office  contents.  The  Telephone  Building,  on  Bush  street 
(PI.  XLI,  A) , met  a similar  fate,  being  consumed  from  within.  This 
new  structure  was  claimed  to  have  the  best  fire  protection  in  the  city. 

The  importance  and  value  of  real  protection  will  be  appreciated 
when  it  is  stated  that  a third-class  building  with  a complete  fire- 
prevention  plant  is  insured  for  less  than  a first-class  one  that  does 
not  have  it.  This  fact  should  be  understood  by  all  owners.  More- 
over, all  parts  of  an  establishment  should  be  equally  protected,  for 
the  fire  may  begin  anywhere.  The  new  Telephone  Building  was 
burned  owing  to  the  nonobservance  of  this  rule,  catching  fire  through 
the  unprotected  wooden  back  door  of  the  basement.  The  structure 
was  fitted  with  “ tin-clad  shutters  ” and  wire  glass  on  the  side  and 
rear  openings  and  with  steel  rolling  shutters  in  front.  The  fire  broke 
through  the  rear  wooden  door  into  two  well  shafts  and  a corridor 
and,  rushing  upward,  consumed  every  floor.  The  building  was 
destroyed  by  a fire  that  entered  through  a single  unprotected  open- 
ing. The  tin-clad  shutters  were  destroyed  and  much  of  the  wire 
glass  was  melted  or  broken  by  the  hot  fire.  The  rolling  shutters  in 
front  still  hung,  but  were  bent  so  that  the  windows  were  exposed. 

Concrete  floors  with  metallic-mesh  reenforcement  are  strongly 
recommended  for  strength  and  fireproof  character.  Noncombustible 
wooden  floors,  doors,  and  trim  were  installed  in  a few  buildings,  and 
under  ordinary  conditions  would  probably  have  limited  the  destruc- 
tion to  “ one-room  fires,”  but  the  heat  was  so  high,  and  in  general 
the  bulk  of  papers,  books,  and  furniture  so  great,  that  all  were 
consumed.  A noninflammable  substitute  for  woodwork  and  trim 
generally  is  greatly  to  be  desired. 


156 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE. 


Double  windows  of  wire  glass  in  hollow  metallic  frames  are  recom- 
mended, or  where  such  material  would  be  objectionable  by  cutting 
off  the  view,  double  plate  glass  is  considered  next  best.  Interior 
doors  should  be  of  metal,  or  at  any  rate  metal  covered,  in  fireproof 
buildings,  and  the  light  for  corridors  and  halls  should  come  through 
wire  glass.  As  the  installation  of  wire  glass,  metallic  rolling  shut- 
ters, and  metal  sash  involves  only  a small  percentage  of  the  cost  of 
the  building,  and  as  these  materials  have  proved  to  be  of  such  excel- 
lent service  as  fire  jDrotection  when  of  the  best  quality  and  workman- 
ship, a wise  economy  demands  their  use  in  every  important  fireproof 
building. 

Capitalists  and  owners  must  understand  that  perfect  fire  protection 
for  structural  steel  is  necessarily  expensive.  Any  so-called  fireproof- 
ing that  is  cheap  and  flimsy  is  a delusion  and  will  not  serve.  The 
application  of  an  effective  method  insures  permanence  of  the  struc- 
ture and  at  the  same  time  greatly  reduces  the  rates  of  insurance. 
Steel  columns  may  be  well  fireproofed  by  surrounding  them  with  the 
best  quality  of  stone  or  cinder  concrete  4 inches  in  thickness,  or  by 
3 inches  of  either  when  hollow  tiling  is  put  on  the  exterior. 

A 3-inch  porous  terra-cotta  tiling,  wrapped  on  the  outside  with 
wire,  and  with  metal  mesh  used  around  the  bed  course  of  the  column, 
has  proved  efficient.  The  mortar  of  the  tiles  should  contain  a large 
proportion  of  cement,  and  the  tiles  should  be  strongly  anchored  to  the 
columns  to  prevent  their  falling  away  in  earthquake  or  fire  and  so 
leaving  the  steel  exposed. 

In  the  great  fire,  decorations,  trim,  inflammable  oil  paints  and 
varnishes,  in  office  buildings,  aided  materially  in  spreading  the  flames. 
A noninflammable  water-color  paint  that  will  endure  washing  has 
been  recommended. 

Fire  walls  of  brick,  extending  above  the  roofs  of  buildings,  were 
effective  in  resisting  the  spread  of  the  fire;  but  the  support  derived 
from  metal  bands  and  anchors  was  neglected  in  many  such  walls, 
as  in  much  other  masonry  in  San  Francisco ; a large  number  of  them 
fell,  therefore,  during  both  the  earthquake  and  the  fire,  particularly 
those  laid  in  common  mortar.  This  was  also  a common  fate  of 
unsupported  gables  and  towers.  Walls  that  were  well  anchored,  as 
in  the  Union  Trust  Building,  remained  in  perfect  condition. 

Cast-iron  columns  in  some  buildings  endured  the  earthquake  and 
the  fire  fairly  well,  but  undoubtedly  would  have  been  broken  or 
shattered  had  cold  water  been  thrown  upon  them  in  the  midst  of  the 
great  heat.  They  should  no  longer  be  used,  for  at  present  they  cost 
more  than  steel  for  an  equal  factor  of  safety,  and  their  connections 
are  clumsy  and  weak. 

Structures  made  of  concrete  blocks  were  as  a rule  greatly  damaged 


EARTHQUAKE  AND  EIRE  PROTECTION.  157 

or  even  ruined  by  the  earthquake,  owing  to  imperfect  anchorage  and 
failure  to  cohere  at  their  joints  (Pl.  XVII,  A). 

Granite,  sandstone,  and  marble  were  badly  cracked  and  spalled  by 
the  fire,  much  of  the  marble  crumbling  to  powder.  The  granite  piers 
in  the  front  of  the  Hobart  Building  were  nearly  all  chipped  away, 
and  they  are  now  reenforced  by  new  temporary  supports. 

Chemical  fire  extinguishers  were  effectively  used  immediately  after 
the  earthquake  in  some  of  the  uptown  residences,  thereby  preventing 
an  increase  in  the  number  of  fire  centers  at  the  beginning  of  the 
conflagration.  It  is  possible  that  numerous  chemical  engines  and 
locally  installed  chemical  extinguishing  plants  in  the  downtown  dis- 
tricts might  have  greatly  limited  the  spread  of  the  flames,  despite 
the  dearth  of  water. 

FINAL  CONCIiUSIONS. 

EARTHQUAKE  PROTECTION. 

A proper  foundation,  stable  and  firm,  is  of  vital  importance, 
and  particularly  on  soft,  marshy,  or  made  ground  (Pis.  XLIII,  B ; 
XLIV,  A).  Anchoring,  bonding,  and  tying  should  be  practiced 
with  exactness  in  all  masonry.  Steel  framing  should  be  made  heavier 
rather  than  lighter,  and  joints,  connections,  bracing,  and  flooring 
should  be  strongly  united.  Girders  and  columns  should  be  made 
very  stiff  and,  where  practicable,  continuous. 

FIRE  PROTECTION. 

The  lessons  taught  by  the  great  fires  of  Boston,  Chicago,  and  Bal- 
timore have  been  verified  by  San  Francisco’s  experience. 

Fireproofing  should  be  of  the  most  perfect  type,  and  no  reasonable 
expense  should  be  spared  in  its  installation. 

Koofs,  roof  appurtenances,  and  skylights  should  be  given  ample 
protection  against  fires  from  without.  A great  excess  of  fire  hose 
and  apparatus,  beyond  ordinary  needs,  should  be  available.  A strong 
bond  for  fireproof  tiling,  etc.,  for  both  girder  and  column  protec- 
tion, is  essential.  Protection  for  front  windows,  as  well  as  for  side 
and  rear  ones, , is  of  vital  importance.  Good  protection  for  steel 
frames  and  steel  roof  trusses  in  attics  or  other  exposed  or  unusual 
places  should  be  provided.  Liberal  use  should  be  made  of  fire  retard- 
ant in  windows,  doors,  transoms,  etc.  Wise  and  liberal  use  of  con- 
crete and  reenforced  concrete  for  girder  and  column  fireproofing  has 
proved  its  saving  quality.  Interior  fire  protection  and  prevention  by 
wells,  pumps,  sprinklers,  and  water  tanks  vastly  lessen  fire  risk. 


158 


THE  SAN  FRANCTSCO  EARTHQUAKE  AND  FIRE. 


ACKNOWLEDGMENTS. 

Special  acknowledgment  is  due  to  the  following  gentlemen,  who 
have  courteously  aided  in  the  preparation  of  this  paper  with  informa- 
tion and  photographs:  T.  P.  Woodward,  city  engineer  of  San  Fran- 
cisco; Charles  Derleth,  jr.,  associate  professor  of  civil  engineering  in 
the  University  of  California,  and  secretary  of  the  Structural  Associa- 
tion of  San  Francisco;  A.  O.  Leuschner,  professor  of  astronomy, 
University  of  California,  and  member  of  the  California  earthquake 
investigation  commission ; also  Oscar  Maurer,  O.  V.  Lange,  and 
Willard  P.  Worden. 

Thanks  are  also*  due  the  Structural  Association  of  San  Francisco, 
the  California  earthquake  investigation  commission,  the  American 
Builder’s  Review  and  its  Engineering  Supplement,  and  the  New  San 
Francisco  Magazine. 


LIST  OF  PAPERS  RELATING  TO  THE  EARTHQUAKE 

AND  FIRE. 


American  Society  of  Civil  Engineers.  Report  of  a general  committee  and  of 
six  special  committees  of  the  San  Francisco  association  of  members  of  the 
American  Society  of  Civil  Engineers.  The  effects  of  the  San  Francisco  earth- 
quake of  April  18,  1906,  on  engineering  constructions : Am.  Soc.  Civil  Eng., 
Proc.,  vol.  33,  no.  3,  pp.  299-354,  31  pis.,  3 figs.,  March,  1907.  Discussion  by 
Edwin  Duryea  and  others : Idem,  vol.  c>3,  no.  5,  pp.  537-547,  1 pi.,  May,  1907. 

Bauer,  L.  A.  Magnetograph  records  of  earthquakes,  with  special  reference  to 
the  San  Francisco  earthquake,  April  18,  1906 : Terrestrial  Magnetism  and  At- 
mospheric Electricity,  vol.  11,  no.  3,  pp.  135-144,  2 figs.,  September,  1906. 

and  Burbank,  J.  E.  The  San  Francisco  earthquake  of  April  18,  1906, 

as  recorded  by  the  Coast  and  Geodetic  Survey  magnetic  observatories : Nat. 
Geog.  Mag.,  vol.  17,  no.  5,  pp.  298-300,  May,  1906. 

Branner,  John  C.  The  California  earthquake:  movements  along  the  Santa 
Cruz  fault  line : Eng.  News,  vol.  55,  no.  20,  p.  542,  May  17,  1906 ; Palo  Altan, 
May  1,  1906. 

Carey,  Everett  P.  The  great  fault  of  California  and  the  San  Francisco 
earthquake,  April  18,  1906 : Jour.  Geog.,  vol.  5,  no.  7,  pp.  289-301,  6 figs.,  1906. 

Discusses  the  faulting  which  produced  the  San  Francisco  earthquake  and  dis- 
placements along  the  line  of  fracture. 

Christy,  S.  B.  Some  lessons  from  the  [San  Francisco]  earthquake:  Mg.  and 
Sci.  Press,  vol.  92,  no.  17,  pp.  273-274,  April  28,  1906. 

Cooper,  A.  S.  The  [San  Francisco]  earthquake  explained:  Mg.  and  Sci. 
Press,  vol.  92,  no.  24,  pp.  401-402,  June  16,  1906. 

Davidson,  George.  Points  of  interest  involved  in  the  San  Francisco  earth- 
quake : Am.  Phil.  Soc.,  Proc.,  vol.  45,  pp.  178-182,  1906. 

Davison,  C.  The  San  Francisco  earthquake  of  April  18 : Sci.  Am.  Supp.,  vol. 
61,  no.  1586,  pp.  25416-25417,  May  26,  1906. 

Derleth,  Charles,  Jr.  Report  [on  the  San  Francisco  earthquake]  : Eng. 
News,  vol.  55,  no.  18,  pp.  503-504,  May  3,  1906 ; no.  19,  pp.  525-526,  May  10,  1906. 

Some  effects  of  the  San  Francisco  earthquake  on  waterworks,  street 

sewers,  car  tracks,  and  buildings : Eng.  News,  vol.  55,  no.  20,  pp.  548-554,  20 
figs.,  May  17,  1906. 

The  destructive  extent  of  the  San  Francisco  earthquake  of  1906 : Eng. 

News,  vol.  55,  no.  26,  pp.  707-713,  17  figs.,  June  28,  1906. 

Engineering  News.  The  San  Francisco  disaster ; earthquake  and  fire  ruin 
in  the  bay  counties  of  California  : Eng.  News,  vol.  55,  no.  17,  pp.  478-480,  1 fig., 
April  26,  1906. 


159 


160 


THE  SAN  FRANCISCO  EARTHQUAKE  AND  FIRE, 


Fuller,  M.  L.  Comparative  intensities  of  the  New  Madrid,  Charleston,  and 
San  Francisco  earthquakes  (abstract)  : Science,  new  ser.,  vol.  23,  pp.  917-918, 
June  15,  1906. 

Galloway,  J.  D.  The  recent  earthquake  in  central  California  and  the  result- 
ing fire  in  San  Francisco : Eng.  News,  vol.  55,  no.  19,  pp.  523-525,  13  figs.,  May 
10,  1906. 

Gilbert,  G.  K.  The  cause  and  nature  of  earthquakes  : Mg.  and  Sci.  Press,  vol. 
92,  no.  17,  pp.  272-273,  April  28,  1906. 

Heilprin,  Angelo.  The  concurrence  and  interrelation  of  volcanic  and  seis- 
mic phenomena:  Science,  new  ser.,  vol.  24,  pp.  545-551,  Nov.  2,  1906. 

Ingalls,  A.  O.  Earthquakes  and  their  probable  origin : Northwest  Mining 
Jour.,  July,  pp.  2-12,  14  figs.,  1906. 

Presents  a detailed  discussion  of  the  Pacific  coast  earthquakes  from  1888 
to  1898. 

Lawson,  Andrew  C.,  and  others.  Preliminary  report  of  the  [California] 
State  earthquake  investigation  commission : Mg.  and  Sci.  Press,  vol.  92,  no.  24, 
pp.  399-401,  4 figs.,  June  16,  1906 ; Sci.  Am.  Suppl.,  vol.  61,  no.  1590,  pp.  25482- 
25484,  June  23,  1906 ; Science,  new  ser.,  vol.  23,  pp.  961-967,  June  29,  1906. 

Includes  various  data  relating  to  the  geologic  structure  of  the  State  of  Cali- 
fornia and  to  the  earthquake  of  April  18,  1906. 

Leuschner,  A.  O.  The  [San  Francisco]  earthquake:  Mg.  and  Sci.  Press, 
vol.  92,  no.  17,  p.  274,  April  28,  1906. 

Marvin,  C.  F.  The  record  of  the  great  [San  Francisco]  earthquake  written 
in  Washington  by  the  seismograph  of  the  U.  S.  Weather  Bureau : Nat.  Geog. 
Mag.,  vol.  17,  no.  5,  pp.  296-298,  May,  1906. 

Milne,  J.  Seismological  investigations.  Eleventh  report  of  the  committee: 
Brit.  Assoc.  Adv.  Sci.,  Kept.,  1906,  pp.  92-103,  1907. 

Contains  references  to  North  American  earthquakes. 

Moore,  C.  E.  Earthquake  effects  at  Santa  Clara,  Palo  Alto,  and  San  Jose, 
Cal. : Eng.  News,  vol.  55,  no.  19,  pp.  526-527,  4 figs.,  May  10,  1906. 

Omori,  Fusakichi.  Observations  of  distant  earthquakes : Mg.  and  Sci.  Press, 
vol.  92,  no.  24,  pp.  397-398,  June  16,  1906. 

Includes  observations  on  the  San  Francisco  earthquake. 

On  the  great  earthquake  of  April  18,  of  San  Francisco,  1906 : Jour. 

Geog.  (published  by  the  Tokyo  Geog.  Soc.),  vol  18,  no.  215,  pp.  764-777,  Novem- 
ber, 1906.  [In  Japanese.] 

Note  on  the  San  Francisco  earthquake  of  April  18,  1906 : Publications 

of  the  [Japan]  Earthquake  Investigation  Committee  in  Foreign  Languages, 
no.  21,  Appendix  II,  3 pp.,  1 pi.,  Tokyo,  1906. 

On  the  estimation  of  the  time  of  occurrence  at  the  origin  of  a distant 

earthquake  from  the  duration  of  the  first  preliminary  tremor  observed  at  any 
place:  Imperial  Earthquake  Investigation  Committee,  Tokyo,  japan,  Bull., 
vol.  1,  no.  1,  pp.  1-4,  January,  1907. 

Includes  time  data  regarding  the  San  Francisco  earthquake  of  April  18,  1906. 

Preliminary  note  on  the  cause  of  the  San  Francisco  earthquake  of 

April  18,  1906 : Imperial  Earthquake  Investigation  Committee,  Tokyo,  Japan, 
Bull.,  vol.  1,  no.  1,  pp.  7-25,  6 pis.,  9 figs.,  January,  1907. 

Preliminary  note  on  the  seismographic  observations  of  the  San  Fran- 


PAPERS  RELATING  TO  THE  EARTHQUAKE  AND  FIRE.  161 


cisco  earthquake  of  April  18,  1906 : Imperial  Earthquake  Investigation  Com- 
mittee, Tokyo,  Japan,  Bull.,  vol.  1,  no.  1,  pp.  26-43,  6 pis.,  January,  1907. 

Tabulates  seismographic  records  of  the  San  Francisco  earthquake  made  at 
various  earthquake-observation  stations  and  discusses  the  rate  of  transmission. 

Comparison  of  the  faults  in  the  three  earthquakes  of  Mino-Owari, 

Formosa,  and  San  Francisco : Imperial  Earthquake  Investigation  Committee, 
Bull.,  vol.  1,  no.  2,  pp.  70-73,  3 figs.,  1907. 

Ransome.  Frederick  Leslie.  The  probable  cause  of  the  San  Francisco  earth- 
quake : Nat.  Geog.  Mag.,  vol.  17,  no.  5,  pp.  280-296,  11  figs.,  May,  1906 ; Mg.  and 
Sci.  Press,  vol.  92,  no.  24,  pp.  396-397,  1906. 

Describes  the  geologic  structure  of  the  region  surrounding  San  Francisco,  Cal. 

Redway,  Jacques  W.  Some  notes  on  the  San  Francisco  earthquake:  Geog. 
Jour.,  vol.  29,  pp.  436^140,  6 figs.,  1907. 

Reid,  Harry  Fielding.  Records  of  seismographs  in  North  America  and  the 
Hawaiian  Islands.  No.  Ill : Terrestrial  Magnetism  and  Atmospheric  Elec-' 
tricity,  vol.  11,  no.  4,  pp.  185-197,  December,  1906. 

[Rickard,  T.  A.]  The  [San  Francisco]  earthquake:  Mg.  and  Sci.  Press,  vol. 
92,  no.  17,  pp.  270-272,  April  28,  1906. 

After  the  [San  Francisco  earthquake]  disaster:  Mg.  and  Sci.  Press, 

vol.  92,  no.  18,  pp.  287-288,  May  5,  1906. 

Former  earthquakes  and  their  discarded  lessons : Mg.  and  Sci.  Press, 

vol.  92,  no.  18,  pp.  289-290,  May  5,  1906. 

and  others.  After  earthquake  and  fire.  A reprint  of  the  articles  and 

editorial  comment  appearing  in  the  Mining  and  Scientific  Press  immediately 
after  the  disaster  at  San  Francisco,  April  18,  1906.  San  Francisco,  Mining  and 
Scientific  Press,  1906.  194  pp.,  illus. 

A reprint  of  papers  appearing  in  the  Mining  and  Scientific  Press  in  the  issues 
of  April  28,  May  5,  and  June  16,  in  the  main  relating  to  the  San  Francisco 
earthquake. 

See,  T.  J.  J.  The  cause  of  earthquakes,  mountain  formation,  and  kindred 
phenomena  connected  with  the  physics  of  the  earth : Am.  Phil.  Soc.,  Proc., 
vol.  45,  pp.  274-414,  17  figs.,  1906. 

Storms,  W.  H.  Earthquake  lines:  Mg.  and  Sci.  Press,  vol.  92,  no.  18,  p.  289, 
May  5,  1906. 

Taber,  Stephen.  Some  local  effects  of  the  San  Francisco  earthquake:  Jour. 
Geol.,  vol.  14,  no.  4,  pp.  303-315,  9 figs.,  1906. 

Describes  the  faulting  which  caused  the  earthquake  and  its  movements  as 
shown  by  various  local  displacements. 

Weatherbe,  D’Arcy.  First  observations  of  the  [San  Francisco  earthquake] 
catastrophe : Mg.  and  Sci.  Press,  vol.  92,  no.  17,  pp.  275-276,  April  28,  1906, 


. 


INDEX. 


A.  Page. 

Academy  of  Sciences,  damage  to 31,  76 

views  of Pis.  XXIV,  XXV 

Acknowledgments  to  those  aiding 63- 

64,  158 

JEtna  Building,  damage  to  — 31-32,  76-77 

views  of Pis.  XXIV,  XXV,  XXIX 

Agnew,  insane  asylum  at,  damage 

to 22,  133 

damage  to,  cause  of 22 

Air  shafts,  danger  from 155 

view  of PI.  XLIX 

Albert  Pike  Memorial,  damage  to 26 

Alluvial  soil,  buildings  on,  damage 

to,  view  of Pi.  XII 

slipping  of,  view  of PI.  VIII 

See  also  Made  ground  ; Settling 
of  soil. 

Appraisers’  warehouse,  damage  to — 32, 

77-78 

view  of  — PI.  XXVIII 

A.rches,  behavior  of,  views  show- 
ing  Pis.  XVIII,  XX 

Arches,  iron,  expansion  of 36,87-88 

Aronson  Building,  damage  to 32, 

78-79,  145 

■ view  of PI.  XXVII 

Attics,  floors  of,  danger  in 122 

B. 


Baltimore,  fire  at,  heat  of 68-69 

fire  at,  loss  in 61 

rebuilding  of 61 

vaults  in 70 

Band  iron,  value  of 26,  27 

Basement  floor,  apparent  pushing 

up  of 32,  77 

Bekins  Van  and  Storage  Co.’s  build- 
ing, character  of 109,  150 

damage  to 33,  109,  147,  150 

view  of Pi.  XXVII 

Bending  moment,  maximum,  point  of 

application  of 15, 

75-76,  143-144 


Berkeley,  damage  at 25,  133 

Bibliography  of  earthquake 159-161 

Bolinas  Lagoon,  fissures  at,  views 

of PI.  IV 

Bracing,  importance  of 15, 

24-25,  26,  35,  57, 

59,  124-125,  144,  151 
instances  of 106-107 


Page. 

Bracing,  lack  of,  results  of,  views 

showing Pis.  XVI,  XVIII 

Brick  buildings,  effect  of  earthquake 

on 57, 

73-75,  110,  135-136,  151 
effect  of  earthquake  on,  view 

showing PI.  XXVIII 

See  also  Brickwork. 

Bricks,  arch,  buildings  of,  survival 

of 110 

Brickwork,  comparative  behavior  of 
reenforced  concrete 

and PI.  XIV 


cracks  in 57,  74-75 

view  of PI.  XXII 

effects  of  earthquake  on 53, 

74,  75,  88,  94-95,  102, 
106,  110,  130,  148-149 

views  showing Pis.  XII,  XX- 

XXII,  XXXVII, XLVI,  LIII 
effects  of  fire  on_  70,  72,  88,  92,  95,  156 

views  showing Pis.  XL,  LII 

essentials  of 59,  152—153 

fireproof  vault  of,  view  of PI.  LII 

fireproofing  by 119, 149-150,  156 

use  of,  in  partitions 52,  72 

See  also  Brick  buildings  ; Bricks, 
arch. 

Bridges,  damage  to 20,  116,  133 

damage  to,  view  showing PI.  XI 

Bryant  street,  settling  in 26 

Building  code,  character  of 50-51, 

59-60,  65-66 


Buildings.  See  Brick  buildings; 

Structures  ; Tall  build- 
ings ; Wooden  build- 
ings. 

Bullock  & Jones  Building,  damage 


to 33,  80-81 

view  of — PI.  XXVI 

Burned  district,  map  showing-  Pis.  LVI, 

LVII 

Butler  Building,  damage  to 109 


views  of___ Pis.  XXX,  XXXIII 


C. 


California  Casket  Co.’s  building, 

damage  to 33-34 

damage  to,  view  of PI.  XXIX 

California  earthquake  investigation 
commission,  personnel 
Of 2 


163 


164 


INDEX, 


Page. 

California  Electric  Co.’s  building, 

fire  protection  of 154 

Call  Building,  damage  to 34,  81-83, 

144,  145,  146,  155 

description  of 34,  81 

Cast  iron,  objections  to — 156 

See  also  Columns. 

Cathedral,  St.  Dominic,  damage  to__  27 
Ceilings,  behavior  of_  passim  31-48,76-108 
behavior  of,  views  showing-  Pis.  XXVI, 

XXXV 

recommendations  on 121 

Cemeteries,  damage  in 29 

Charleston  earthquake,  cause  of 2 

Chemical  extinguishers,  value  of 157 

Chimneys,  damage  to__  21,  24,  100,  111-112 
See  also  Smokestacks. 

Chittenden,  railroad  bridge  at,  dam- 
age to T 20 

Chronicle  Building,  damage  to 35, 

83-84,  144 

view  of PI.  XXX 

Cinder  concrete.  See  Concrete. 

City  hall,  damage  to 35—36,  69,  84—89 

description  of_ — 84-86 

restoration  of,  cost  of 89 

ruins  of,  views  of — Pis.  XXVI,  XXXI 
College  Hill  reservoir,  conduit  to, 

damage  to 18 

Columns,  failure  of,  through  fire — passim 
30-48,  72,  78-104 
failure  of,  through  fire,  views 

showing--  Pis.  XXVI,  XXVII, 
XXXIV-XXXVI, 
XL,  XLVIII-L 

fireproofing  of 52,  71-72,  156 

damage  to,  by  earthquake-  74 

failure  of,  through  fire passim 

30-48,  72,  78-104 

views  showing Pis.  XXIV, 

XXVII,  XXIV-XXVI, 
XL,  XLIII 

recommendations  on 55,  72 

See  also  Pilasters. 

Commissary  building.  See  2Etna 
Building. 

Concrete,  behavior  of,  in  earthquake. 

See  Concrete,  reen- 
forced. 

behavior  of,  in  fire 31—33, 

43-44,  46,  52-55,  72-74,  79, 
103-104,  119-121,  147-148 
views  showing — Pis.  XXIV,  XXV 
Concrete,  reenforced,  comparative 
behavior  of  brickwork 
and,  view  showing — PI.  XIV 

behavior  of 15,  22-24,  29-30, 

33,  44,  75,  77,  80-82,  87-88, 
97,  108,  113,  130,  150,  152 

views  showing Pis.  XX, 

XXIII,  XXV,  XXVI,  XXVII 
example  of.  See  Bekins  Van 
and  Storage  Co. 

merits  of— ^ 52,  58,  60,  75,  107,  109, 
120-121,  125-126,  150,  152 

opposition  of  union  labor  to 60, 

126,  150 


Page. 

Concrete  buildings,  behavior  of 15,  24, 

29-30,  33,  75,  113,  150,  152 

Concrete  dam,  view  of PI.  XI 

Concrete-block  buildings,  damage  to_  24-25, 
113,  114,  156-157 

damage  to,  views  showing Pis.  XVII, 

XIX 

Conduits  and  mains,  damage  to 18-19, 

115-116 

damage  to,  views  showing Pis.  IX,  X 

map  showing PL  LVII 

repairs  to 117-118 

Construction,  defects  of,  wide  preva- 
lence of 60 

rigidity  of,  necessity  for,  in  high 

structures 15,  59 

Court-house,  Santa  Rosa,  ruins  of, 

view  of PI.  XIV 

Cowell  Building  damage  to 89,  146 

view  of PI.  LI 

Cracks,  earth,  character  of 7 

view  of PI.  IV 

Cracks,  masonry,  character  of_  26,  57,  74-75 

views  of Pis.  XXII, 

XXX,  XLIII,  XLIV,  LIII 

Crocker  Building,  damage  to 36,  89-90 

view  of PL  LII 

Crocker  Estate  Building,  damage  to_  90 

view  of PI.  XXVIII 

Crystal  Springs  Lake  dams,  immu- 
nity of 19,  114-115 

view  of PI.  XI 

Custom-house,  United  States.  See 
Appraiser's  warehouse. 

Cyclorama,  collapse  of 29—30,  109 

views  of Pis.  XXII,  XXIII 


D. 


Dams,  damage  to 18-19,  21,  114-115,  116 

safety  of 126 

view  of PL  XI 

See  also  Reservoirs. 

Dewey  monument,  damage  to 90 

view  of PL  XXX 

Doors,  metal-covered,  efficacy  of 94 

Dore  street,  settling  in 26 

settling  in,  view  of. Pl.  VI 

Dynamiting,  damage  done  by 101 

damage  done  by,  view  show- 
ing   Pl.  XLVIII 

inefficacy  of 56,  66—67,  137—138 


E. 


Earth,  flow  of 7-9 

flow  of,  results  of,  views  of — Pis.  V, 
VII,  VIII,  XLII,  XLIII 
See  also  Settling  of  soil ; Made 
ground. 

Earth  waves,  propagation  of_  10-11,  12-13 

velocity  of 17 

Earthquakes,  aftermath  of 59 

causes  of 2 

damage  by,  minimization  of_  150,  157 

insurance  against 129 

nature  of 2 


INDEX. 


165 


Page. 

Earthquakes,  prevalence  of,  on  Pa- 
cific coast 15,  16,  143 

protection  against 15, 

56-59,  116-118,  124-126,  157 

See  also  San  Francisco  earth- 
quake ; San  Francisco, 
earthquake  in. 

Elevator  shafts,  danger  from 155 

Emanuel  Synagogue,  damage  to 26 

view  of__: PI.  XXI 

Emporium,  damage  to 36,  78,  90-91 

views  of PI.  XXXII 

Explosions,  volcanic,  earthquakes 

caused  by 2 


F. 


Fairmount  Hotel,  damage  to 37,  92 

view  of PI.  XXXIV 

Fault  scarp,  description  of 5 

Fault  trace,  antiquity  of 2,  16,  131 

appearance  of 5 

views  of Pis.  I,  II,  III 

character  of,  diagram  showing  _ 4 

conduit  crossing,  views  of Pis.  IX,  X 

description  of 4-6 

dam  on,  effects  of  earthquake 

on 19 

views  of PI.  XI 

distances  from,  to  towns,  etc 6 

earth  movement  along ___  4, 

5,  17,  20,  132-133 

views  showing ; Pis.  I,  II 

extent  of  2,  4,  10,  16-17,  131 

fence  crossing,  view  of PI.  I 

map  of 3 

mapping  (previous)  of 16 

offset  in 5 

views  of Pis.  I,  IX 

reservoirs  on,  damage  to 10—19, 

114-115 

road  crossing,  view  of PI.  I 

telescoping  along,  view  showing-  PI.  IX 
See  also  Faulting. 

Faulting,  earthquakes  due  to 2,  10,  15-16 

prevalence  of,  on  Pacific  coast-  15 
place  of,  surface  or  subterra- 
nean   <___ 2 

time  required  for 11 

See  also  Fault  trace. 

Fire,  protection  against-- 51-56, 

119-124,  126-129,  157 
See  also  San  Francisco,  fire  in  ; 

San  Francisco  fire. 

Fire  extinguishers,  chemical,  value 

of 157 

Fire  Underwriters,  National  Board 
of,  report  of,  on  fire 
hazard  in  San  Fran- 
cisco  49-51 

64,  139-140 

Fireproof  buildings  in  San  Fran- 
cisco, character  of 52 

conditions  surrounding 50,  64 

damage  to 51-52,  66 

protection  of 128-129 


Page. 

Fireproofing,  cost  of 149,  156 

general  inadequacy  of 119,  146,  147 

imperfections  of,  in  San  Fran- 
cisco— 52-54,  71-74,  147-150 

insurance  rates  reduced  by 155 

materials  for 52-54,  147-150 

protection  afforded  by,  percent- 
age of 78 

recommendations  concerning 55 

119-122,  157 

See  also  Brick ; Concrete ; 

Metal  laths  ; Tiles,  etc. 

Fissures,  creation  of 133 

views  of Pis.  Ill,  IV 

Flood  Building.  See  James  Flood 
Building. 

Floors,  behavior  of passim  31-48 

73,  76-108 

behavior  of,  views  showing-  Pis.  XXVI, 
XXVII,  XXIX 

recommendations  on 125,  155 

Fortifications,  damage  to 63,  114 

Foundations,  importance  of 57,  59, 

133,  135,  143,  151 

Frame  buildings.  See  Wooden  build- 
ings. 


G. 


Geologic  formations,  character  of, 

influence  of 12,  133-136 

Gilbert,  G.  K.,  photographs  by_- Pis.  I, 

Ill-Vlbl 

report  by,  on  the  earthquake  as 

a natural  phenomenon.  1—13 

work  of xi 

Girders,  fire  protection  of 73-74,  119 

Girls’  high  school,  damage  to 26-27 

Glass,  wire,  behavior  of 80,  123,  154,  156 

behavior  of,  view  showing PI.  LX 

Golden  Gate  Park,  damage  in 29-30 

Government  buildings,  damage  to 32,  42, 

44-45,  69,  78,  151 

views  of Pis.  XXVIII, 

XXXVIII,  XLIII,  XLIV 

Granite,  damage  to 53,  92,  157 

damage  to,  views  showing-  Pis.  XXIV, 

XXXVI 

Grant  Building,  damage  to 37-38,  93 

Gravity,  earth  movement  due  to 8 

Gravity  waves,  propagation  of  10-11,  12-13 
Greek  Theater,  immunity  of 25 

H. 

Hahnemann  Medical  College,  dam- 
age to 27 

Hayward  Building,  damage  to 40 

Hibernia  Savings  and  Loan  Soci- 
ety’s building,  damage 

to 38,  108 

view  of— PI.  XXXVII 

High  school  building,  San  Jose, 

damage  to,  view  of PI.  XIII 

Himmelwright,  A.  L.  A.,  photograph 

by PI.  XXXVI 


7171— Bull.  324—07- 


-12 


166 


INDEX. 


Page. 

Hobart  building,  damage  to 38-39 

view  of PL  XXXVI 

Hollow  tile.  See  Tiles. 

Holmes,  J.  A.,  preface  by xi-xii 

Horne  store,  Pittsburg,  comparison  of 

fires  at  Emporium  and_  91 

Hotel  Hamilton,  damage  to 38 

view  of PI.  XXXVI 

House,  splitting  of 20 

splitting  of,  view  showing PI.  X 

Howard  street,  ruined  buildings  on, 

view  of PI.  LIII 

settling  in 26 

view  showing PI.  VI 

Humphrey,  R.  L.,  experience  of xi 

maps  by Pis.  LVI,  LVII 

photographs  by  _ Pis.  II,  VI,  X- 

XXV,  XXVII-XXX,  XXXIV- 
XLV,  XLVIII,  L,  LII-LIII 
report  by,  on  effects  of  earth- 
quake and  fire  on 
structures  and  struc- 
tural materials 14-61 

work  of 14 


I. 


Illustrations,  sources  of iv 

Insurance,  earthquake,  need  for 129 

Intensity,  earthquake,  definition  of_  12 

distribution  of 12-13 

factors  governing 132—136 

maximum  of,  region  of 2,  4,  132-133 

scale  of 16,  131 

variations  in  66,  75,  109 

Inyo  earthquake,  cause  of 2 

Iron  arches,  expansion  of 36,  87-88 


J. 


Jackson  Brewing  Company’s  build- 
ing, damage  to 39 

view  of PI.  XXXVII 

James  Flood  Building,  damage  to 37, 

78,  92-93,  145,  146-147,  148 

views  of Pis.  XXXIII,  XXXV 

Japan,  gravity  waves  in 13 

Jerkiness,  causes  of 11-12 

Justice,  Hall  of,  at  San  Francisco, 

damage  to 39,  93 

view  of Pis.  XXXV,  XXXIX 

Justice,  Hall  of,  at  San  Jose,  wreck 

of,  view  of PL  XII 

K. 

Kamm  Building,  damage  to 39-40,  93 

Kelly,  William,  information  from 124 

Key  monument,  damage  to 29 

view  of Pl.  XX 

Kohl  Building,  damage  to 40,  94,  152 

L. 

Labor  unions,  attitude  of 60,  126,  150 

Lake  Honda  reservoir,  conduit  to, 

destruction  of 18 

damage  to „ 19,  115 


Page. 

Landslips,  production  of 8 

Laths,  metal.  See  Metal  laths. 

Lawson,  A.  C.,  faults  traced  by 16 

photographs  by Pis.  VIII,  XIII 

Lee  Brothers,  building  of,  view  of _ Pl.  XVII 
Leland  Stanford  Junior  University, 

damage  to 22-24, 

75,  112-114,  133 
damage  to,  views  of_  Pis.  XIV-XVIII 

geologic  conditions  at 15 

Leuschner,  A.  O.,  on  San  Francisco 

earthquake 143 

Life,  loss  of 60-61,  153 

Light-houses,  damage  to 63 

Los  Gatos,  tunnel  near,  damage  to 20 


M. 


Made  ground,  conduits  in 118 

movement  of 8,  13,  15,  21,  133 

effect  of,  on  structures 15, 

19,  26,  56,  115-116,  133,  135 

views  of Pis.  V,  VI 

sewers  in H8 

See  also  Settling  of  ground ; 

Earth. 

Mains  and  conduits,  damage  to 18-19, 

115-116,  133 

damage  to,  views  of Pis.  IX,  X 

repair  of 117-118 

Majestic  Theater,  damage  to 40 

view  of Pl.  XXXIX 

Marble,  destruction  of 53,  157 

Marston  Building,  lessons  from 152 

Marx,  C.  D.,  and  Wing,  C.  B.,  report 

of * 63,  114-116 

Masonry.  See  Stonework ; Brick- 
work. 

Materials,  structural,  behavior  of 51-55, 

71-76 

See  also  particular  materials; 

Structures,  artificial. 
Mercantile  Trust  Co.’s  building,  dam- 
age to 40 

Merchants’  Exchange  building,  dam- 
age to 41,  94-95 

view  of Pl.  XL 

Metal  (expanded)  and  plaster,  fire- 
proofing by 40, 

45,  47,  93,  104,  119,  148-149 

partitions,  ceilings,  etc.,  of 44, 

47,  77,  90,  104 

Metal  laths  and  plaster,  behavior  of, 

views  showing — Pis.  XXXIV, 
XLI,  XLVIII 

fireproofing  by 38, 

39,  73-74,  93,  148-149 

partitions  and  ceilings  of 43,  46,  92 

Mill  construction,  definition  of 66 

failure  of 36,  90-91,  152-153 

view  showing Pl.  XXXII 

Mills  Building,  damage  to 41-42,  78,  148 

damage  to,  views  of Pis.  XL,  XLV 

Mills  College  for  Girls,  damage  to 25 

damage  to,  view  of Pl.  XX 


INDEX, 


167 


Page. 

Mint,  United  States,  damage  to 42, 

95-96,  154-155 

view  of PI.  XXXVIII 

Mission,  The,  section  of  city  known 

as 137 

Mission  Dolores,  new,  damage  to 27 

old,  view  of PI.  XXIII 

Mission  street,  earth  slip  on,  view 

showing PI.  XLIII 

Monadnock  Building,  damage  to 42,  96 

repairs  to 42-43 

Monterey,  damage  at 21 

Monterey  Bay,  effects  of  earthquake 

at 21 

Mosaic  ceilings,  behavior  of 45 

Mountain-making  forces,  earthquakes 

due  to 2 

See  also  Tectonic  earthquakes. 

Mud,  movement  of 8-9 

See  also  Earth. 

Murphy  Building,  damage  to 43 

view  of PI.  XLI 

Mutual  Life  Building,  damage  to 43,  96 

view  of PI.  XLII 

Mutual  Savings  Bank,  damage  to 108 

N. 

New  Madrid  earthquake,  cause  of 2 

Ninth  street,  earth  flow  on,  view  of_  PI.  V 

O. 

Oakland,  damage  at 25,  112,  133 

Omori,  F.,  on  earthquakes 59,  132,  143 

Ornamentation,  loss  on 52-53,  127,  154 

P. 

Pacific  States  Telephone  and  Tele- 
graph Co.’s  building, 
damage  to_  43-44,  96-97,  155 


view  of PI.  XLI 

Pajaro  River,  railroad  bridge  over, 

damage  to 20 

damage  to,  view  of PI.  XI 

Palace  Hotel,  damage  to 26,  97,  149-150 

views  showing Pis.  XXX,  LII 

Palo  Alto,  damage  at 24,  114 

geologic  conditions  at 15 


See  also  Leland  Stanford  Jun- 
ior University. 

Partitions,  behavior  of.  See  Metal 
laths ; Terra  cotta ; 

Tiles,  etc. 

general  character  of 52,  72-73,  94 

recommendations  concerning 55, 

125, 127-128 

Pike  (Albert)  Memorial,  damage  to_  26 
Pilarcitos  conduit,  damage  to.  18,  115,  133 

damage  to,  views  showing Pis.  IX,  X 

Pilasters,  shearing  of 85,  96 

stripping  of,  view  showing PI.  XII 

Piles,  buildings  on,  damage  to 28,  135 

Pipes  on  columns,  damage  due  to 45 

52,  80,  148 

Plaster  of  Paris,  effect  of  fire  on 31 

effect  of  fire  on,  view  showing.  PI.  XXV 


Page. 

Plastering,  imperfections  of 88 

Plumb,  difficulty  of  building  in_  82-83,  130 

Point  Arena,  fault  trace  at 2 

fault  trace  at,  map  showing 3 

Point  Delgada,  fault  trace  at 2 

Point  Reyes,  fault  trace  near,  views 

of Pis.  I,  III 

Post-office  building,  damage  to 44-45, 

97-103 

settlement  at 99 

views  of Pis.  XLII,  XLIII,  XLIV 

Publications  on  earthquake,  list  of_  159-161 

R. 

Rafters,  thrust  of,  damage  from 114 

damage  from,  view  showing PI.  XIX 

Railroads,  damage  to 20,  21 

damage  to,  view  showing PI.  XI 

Records,  hall  of,  San  Francisco,  dam- 
age to 36,  89 

Records,  hall  of,  Santa  Rosa,  ruins 

of,  view  of PI.  XIV 

Redwood,  damage  at 114 

Reed,  S.  A.,  on  fire  in  telephone 

building 97 

Reservoirs,  damage  to 18-21,  114-116 

See  also  Water-supply  systems. 

Rhythm  of  earthquake,  character 

of 11-12 

Rialto  Building,  damage  to 45,  103 

view  of PI.  XLVIII 

Rivets,  importance  of 144 

shearing  of,  view  showing.  PI.  XLVII 
Roberts,  J.  W.,  aid  of 44,  97-98 

S. 

Safes,  failure  of — — 53,  69-71,  124 

failure  of,  view  showing PI.  LII 

Sailors’  Home,  damage  to 27 

St.  Dominic  Cathedral,  damage  to 27 

St.  Francis  Hotel,  damage  to 45-46, 

103-104 

Salinas,  damage  at 21,  133 

geologic  conditions  at 15 

Salinas  River,  effects  of  earthquake 

near 21,  133 

effects  of  earthquake  near,  view 

showing PI.  VIII 

Salt  - water  mains,  establishment 

of 117,  139,  153 

San  Andreas  dam,  damage  to 18—19,  115 

San  Francisco,  area  of 134 

building  code  in 50-51,  59-60',  65-66 

buildings  in,  character  of 30,  50, 

52,  59,  65,  134-136,  139-142 

classes  of 65-66 

relative  damage  to 57—58 

fire  underwriters’  report 

on 49-50,  64,  139-140 

height  of 142 

recommendations  for 124-129 

See  also  Structures,  arti- 
ficial. 

description  of 141-142 

earthquake  in,  damage  by 25-48, 

72,  112,  142-145 


168 


INDEX, 


Page. 

San  Francisco,  earthquake  in,  dam- 
age by,  reasons  for_  26,  58,  142 
earthquake  in,  damage  by,  re- 
lation of  fire  damage 

and 66,  74,  153 

effect  of,  on  walls.  See 
Cracks. 

lessons  of 56-59 

loss  of  life  in 59-60,  153 

See  also  San  Francisco 
earthquake. 

fire  department  of 51,  140,  153 

chief  of,  death  of 137 

fire  hazard  in,  underwriters’  re- 
port on 49-51,  64,  139-140 

fire  in,  normal  loss  by 49,  136,  139 

normal  loss  by,  reasons 

for 138-139 

See  also  San  Francisco  fire, 
fireproof  buildings  in,  behavior 
of.  See  Fireproof 
buildings. 

foundation  material  of 25,  134—136 

map  of,  showing  burned  area_  PI.  LYI 
showing  whole  city,  burned 
area,  water  conduits, 

etc PI.  LVII 

panorama  of PI.  LY 

population  of 134 

rebuilding  of 59-60,  61,  116-117 

recommendations  for 124—129 

surviving  buildings  in,  descrip- 
tions of 31-48,  76-112 

view  of,  from  Pine  and  Powell 

streets PI.  LV 

from  Telegraph  Hill PI.  LIV 

water  supply  system  of 17-18, 

19-20,  50,  139 

damage  to 18-20,  137 

causes  of 19 

future  prevention  of 19—20, 

55,  153 

fire  underwriters’  report  on_  50, 
117,  139 

map  showing PI.  LVII 

recommendations  on 117,  153 

San  Francisco  earthquake,  beginning 

of,  point  of 132 

bibliography  of 159-161 

cause  of 2,  132 

consideration  of,  as  a natural 

phenomenon 1-13 

damage  by 17-25, 

30-48,  72-116,  150-152 

date  of 14,  131 

direction  of 17,132 

duration  of 16,  131-132 

effect  of,  on  surface  material __  7-9 

extent  qf_. 2,  4,  10,  16,  132 

map  showing 3 

intensity  of.  See  Intensity. 

movements  in,  character  of 10—12, 

17,  26 

direction  of 17,  132 

extent  of 4-5,  10,  17,  132,  143 

See  also  Fault  trace. 


Page. 

San  Francisco  earthquake,  publica- 
tions on 159-161 

shocks  in,  number  of . 16,  131 

velocity  of 17 

vibrations  in 10-12,  17 

See  also  Fault  trace ; Faulting ; 

San  Francisco,  earth- 
quake in ; and  par- 
ticular towns. 

San  Francisco  fire,  comparison  of 

other  fires  and 51 

damage  by 30-48,  59-60,  61,  66, 

69-108,  126-127,  146-150 

insurance  for 59 

loss  from 138,  153 

relation  of  earthquake  dam- 
age and 66,  74,  153 

See  also  Structures,  arti- 
ficial. 

description  of _ 136-139 

fireproof  buildings  in.  See  Fire- 
proof buildings. 

heat  of 51,68-69 

lessons  of 56-59 

loss  from 138,  153 

magnitude  of 49,  137-138 

maps  showing Pis.  LVI,  LVII 

wind  caused  by 137 

See  also  San  Francisco,  fire  in. 

San  Francisco  Gas  and  Electric 
Light  Co.,  buildings  of, 

damage  to 27-28 

San  Jose,  damage  at 21-22,  133 

damage  at,  reasons  for 22 

views  showing Pis.  XII,  XIII 

geologic  conditions  at 15 

reservoir  of,  damage  to 21,  116 

San  Juan,  fault  trace  at 2 

San  Mateo,  dam  near,  escape  of 19 

dam  near,  view  of Pi.  XI 

Sandstone,  damage  to 53,  92-93,  157 

Santa  Rosa,  damage  at 24-25,  133 

damage  at,  reasons  for 25 

view  showing PI.  XIV 

geologic  conditions  at 15 

Santa  Rosa  Valley,  earthquake  in 4 

Saratoga  reservoir,  damage  to_ 21,  116 

Schussler,  Herman,  aid  of 18 

Scott  Building,  damage  to 46 

Searsville  dam,  immunity  of 19,  115 

Security  Savings  Bank,  damage  to 46 

Settling  of  soil 9,  21,  44 

effect  of 15,  26,  32,  77 

views  of Pis.  IV, 

VI,  VIII,  XXV,  XLII,  XLIV 
See  also  Made  ground  ; Earth. 

Sewell,  J.  S.,  experience  of xi 

photographs  by Pis.  XXI. 

XXV,  XXVI,  XXVIII, 
XXX,  XXXII.  XXXIII, 
XXXV,  XXXVIII,  XXXIX, 
XLIII,  XLIV,  XLIX,  LV 
report  of,  on  effects  of  earth- 
quake and  fire  on  build- 
ings, engineering  struc- 
tures, and  structural 

-materials 62-130 

work  of 62 


INDEX. 


Page. 

Sewers,  recommendations  regarding-  118 

Shafts,  air,  danger  from 155 

view  of PI.  XLIX 

Shreve  Building,  damage  to 46,  104 

Shutters,  importance  of_  122-124,  154-155 

use  of,  in  San  Francisco 123-124 

Sloane  Building,  damage  to 47,  104 

view  of - PI.  XLIX 

Slow-burning  construction.  See  Mill 
construction. 

Smokestacks,  damage  to 112 

views  of Pis.  XIII,  LI  1 1 

Soil.  See  Earth ; Made  ground ; 
Settling. 

Soule,  Frank,  experience  of xi 

photographs  by Pis.  IX, 

XII,  XXXI,  LIII,  LIV 

report  by,  on  the  earthquake 
and  fire  and  their  ef- 
fect on  structural  steel 
and  steel-frame  build- 
ings   131-158 

Southern  Pacific  Railroad,  damage 

to 20,  114 

damage  to,  view  showing PI.  XI 

Spreckels  (Claus)  Building.  See 
Call  Building. 

Spreckel’s  sugar  mill,  damage 

to 21 

damage  to,  view  showing PI.  XII 

Spring  Valley  Water  Co.,  building 

of,  damage  to 47, 

78,  104-105 

building  of,  damage  to,  views 

of Pis.  XLV,  L 

vault  in 70 

conduits  and  mains  of,  damage 

to 62-63,  115-116 

damage  to,  views  show- 
ing   Pis.  IX,  X,  XI 

danls  of,  damage  to 62,  114-115 

Stairways,  behavior  of 105 

Stanford  University.  See  Leland 
Stanford  Junior  Uni- 
versity. 

Steel,  structural,  reliability  of 145—146 

Steel  bands,  effect  of  fire  on 31-32 

effect  of  fire  on,  view  show- 
ing   PI.  XXIX 

Steel  buildings,  effect  of  earthquake 

on 57—58,  75—76, 

130,  136,  142,  144,  151-152 
effect  of  earthquake  on,  views 

showing Pis.  XV,  XXXIII 

effects  of  fire  on passim  30-49, 

76-112,  146-147 

view  showing : PI.  LI 

fireproofing  of.  See  Fireproof- 
ing. 

joints  in,  damage  at 75-76 

Slone  buildings,  effect  of  earthquake 

on 22—24, 

57,  58,  74,  75,  85,  112-113 
effect  of  earthquake  on,  view 

showing PI.  XII 


169 

Page. 

Stone-veneer  buildings,  damage  to 22—24, 

58,  113,  145 

Stonework,  effect  of  earthquake  on_  53, 

74,  75,  145 

effect  of  earthquake  on,  views 

showing-  Pis.  XXXIII,  XLIV 
effect  of  fire  on,  views  show- 
ing ___  Pis.  XXXVII-XXXIX 

essentials  in 59 

Stow  Lake,  bridge  over,  immunity 

of 30* 

Structural  materials,  behavior  of 51-55, 

71-76 

See  also  particular  materials. 
Structures,  artificial,  classes  of,  rela- 
tive damage  to 57-58, 

74-75,  150-152 

cracks  in 26,  74,  75 

defects  prevailing  in 60 

comparative  endurance  of,  view 

showing PI.  XIII 

essentials  of,  for  resisting  earth- 
quake and  fire 15, 

56-59,  116-118,  124-126,  157 

failures  of,  causes  of 58,  150—152 

fire  risk  of 153-154 

protection  of,  against  fire 51-56, 

119-124,  126-129,  157 

against  outside  fires 54-55 

surviving,  descriptions  of 31—48 

susceptibility  of,  to  earthquake-  12, 

15,  75 

water  supply  for 54-55,  122,  128 

See  also  Concrete ; Stone ; Tall 
buildings,  etc. 

Structures,  artificial,  in  San  Fran- 
cisco, effect  of  earth- 
quake and  fire  on 25—48, 

69-112 

See  also  particular  structures. 
Structures,  artificial,  outside  San 
Francisco,  effect  of 

earthquake  on 17-25, 

63,  112-116 

See  also  particular  places. 

Subtreasury,  United  States,  damage 

to 47 

Surface  material,  movements  of_ 7-9 

Synagogue  Emanuel,  damage  to 26 

view  of PI.  XXI 

T. 

Tall  buildings,  properly  built,  safety 

of 58,  75,  129,  152 

recommendations  on 124—125 

Tanks,  survival  of,  view  showing-  PI.  XIII 

wrecking  of 21,  116 

Tectonic  earthquakes,  character  of 15-16 

Temperatures,  range  of 51,  68-69 

Terra  cotta,  ornamental,  failure  of, 

view  showing PI.  XXVIII 

See  also  Tiles,  terra-cotta. 

Thiele  Building,  destruction  of 24 

ruins  of,  view  of PI.  XIX 


170 


INDEX, 


Page. 

Tie,  lack  of,  results  of,  views  show- 
ing  Pis.  XVI,  XIX 

value  of,  view  showing PI.  XVII 

Tiles,  terra-cotta,  behavior  of,  in 

floors,  partitions,  etc_  passim 
35-48,  73-95,  101- 
102,  105,  130 

behavior  of,  views  showing-  Pis.  XLV, 

XLIX,  L 

fireproofing  by passim 

32-37,  46-54,  70-95, 
119-120,  148,  156 

failure  of,  consequences  of, 

views  showing Pis.  XXYI, 

XXVII,  XL,  XLII,  XLV 

quality  of,  on  Pacific  coast 52 

use* of,  in  San  Francisco-  120-121,  148 

varieties  of 148 

Tomales  Bay,  mud  bottom  of,  grav- 
ity waves  in 13 

mud  bottom  of,  shifting  of: 8 

views  of Pis.  VII,  VIII 

Trees,  splitting  of 20,  133 

splitting  of,  view  showing PL  II 

Trim,  loss  on 52-53,  127,  154 

Tunnels,  railroad,  damage  to 20,  62 

U. 

Union  Ferry  Building,  damage  to 28-29 

105-107,  135 

damage  to,  views  showing-  Pis.  XL VI, 

XL  VII 

Union  Savings  Bank,  damage  to 136,  145 

Union  Trust  Co.’s  building,  damage 

to 47-48,  108 

view  of PI.  L 

University  Mound  reservoir,  conduit 
to  and  mains  from, 
damage  to 18 

V. 

Valencia  street  power  station,  dam- 
age to,  view  showing-  PI.  LIII 
Vandervoort  Brothers’  building,  de- 
struction of 24 

view  of PI.  XIX 

Vaults,  failure  of 53,  69-71,124 

failure  of,  views  showing Pis.  XXIX, 

LII 

survival  of,  view  showing PI.  LII 

Vibrations,  character  of 10—12 

direction  of 17 

propagation  of,  velocity  of 17 


Page. 

Volcanic  action,  earthquakes  due 


to  2,  15-16 

Volkman  building,  damage  to 48 


W. 

Walker,  M.  L.,  information  from 124 

Water,  effect  of  earthquake  on 9 

individual  supply  of 54-55, 

122,  128,  154 

ease  of  obtaining,  in  San 

Francisco 122 

Water-supply  systems,  character  of_  17-18, 

19-20,  21,  139 

damage  to 18-21,  117 

prevention  of 19-20, 

55,  56,  117-118,  153 

reasons  for 19 

Water  tower,  damage  to 116 

Waves.  See  Earthquakes. 

Wellington,  G.  J.,  report  of,  on 

fire 140-141 

Wells-Fargo  Building,  damage  to 48 

views  of Pis.  XLIX,  LII 

Whittell  Building,  lessons  from 152 

Wind,  production  of,  by  fire 137 

Wind  bracing,  earthquake  shocks 

taken  up  by 144 

Wing,  C.  B.,  and  Marx,  C.  D.,  report 

of 63,  114-116 

Wire  glass,  behavior  of 80,  123,  154,  156 

behavior  of,  view  showing — PI.  XLIX 
Wire  lath  and  plaster,  fireproofing 

hy_  38,  41,  48,  94,  119,  148-149 
fireproofing  by,  failure  of,  view 

showing PI.  XXXVI 

partitions  of 42,  46,  48,  94 

Wooden  buildings,  effects  of  earth- 
quake on 21, 

57,  60,  110,  135,  151 

essentials  in ' 59,  111 

ruins  of,  views  of PI.  XIV,  LIII 

Woodwork,  loss  on 52 

Woodwork,  metal-covered,  behavior 

of 40,  53,  154,  156 

Wrights,  house  near,  splitting  of 20 

house  near,  splitting  of,  view 

showing : PI.  X 

tunnel  near,  damage  to 20 

Y. 

Young  Building.  See  ^Etna  Building. 


CLASSIFICATION  OF  THE  PUBLICATIONS  OF  THE  UNITED  STATES  GEOLOGICAL 

SURVEY. 

[Bulletin  No.  324.] 


The  publications  of  the  United  States  Geological  Survey  consist  of  (1)  Annual 
Reports,  (2)  Monographs,  (3)  Professional  Papers,  (4)  Bulletins,  (5)  Mineral 
Resources,  (6)  Water-Supply  and  Irrigation  Papers,  (7)  Topographic  Atlas  of  United 
States— folios  and  separate  sheets  thereof,  (8)  Geologic  Atlas  of  United  States — folios 
thereof.  The  classes  numbered  2,  7,  and  8 are  sold  at  cost  of  publication;  the  others 
are  distributed  free.  A circular  giving  complete  lists  can  be  had  on  application. 

Most  of  the  above  publications  can  be  obtained  or  consulted  in  the  following  ways: 

1.  A limited  number  are  delivered  to  the  Director  of  the  Survey,  from  whom  they 
can  be  obtained,  free  of  charge  (except  classes  2,  7,  and  8),  on  application. 

2.  A certain  number  are  delivered  to  Senators  and  Representatives  in  Congress  for 
distribution. 

3.  Other  copies  are  deposited  with  the  Superintendent  of  Documents,  Washington, 
D.  C.,  from  whom  they  can  be  had  at  prices  slightly  above  cost. 

4.  Copies  of  all  Government  publications  are  furnished  to  the  principal  public 
libraries  in  the  large  cities  throughout  the  United  States,  where  they  can  be  consulted 
by  those  interested. 

The  Professional  Papers,  Bulletins,  and  Water-Supply  Papers  treat  of  a variety  of 
subjects,  and  the  total  number  issued  is  large.  They  have  therefore  been  classified 
into  the  following  series:  A,  Economic  geology;  B,  Descriptive  geology;  C,  System- 
atic geology  and  paleontology;  D,  Petrography  and  mineralogy;  E,  Chemistry  and 
physics;  F,  Geography;  G,  Miscellaneous;  H,  Forestry;  I,  Irrigation;  J,  Water  stor- 
age; K,  Pumping  water;  L,  Quality  of  water;  M,  General  hydrographic  investiga- 
tions; N,  Water  power;  0,  Underground  waters;  P,  Hydrographic  progress  reports; 
Q,  Fuels;  R,  Structural  materials.  This  paper  is  the  first  in  Series  R and  bears  the 
following  title  (B=Bulletin) : 


SERIES  R,  STRUCTURAL  MATERIALS. 

B 324.  The  San  Francisco  earthquake  and  fire  of  April  18, 1906,  and  their  effects  on  structures  and 
structural  materials;  reports  by  G.  K.  Gilbert,  R.  I.  Humphrey,  J.  S.  Sewell,  and  Frank 
Soul6,  with  preface  by  J.  A.  Holmes.  1907.  170  pp.,  57  pis. 

Correspondence  should  be  addressed  to 

The  Director, 

United  States  Geological  Survey, 

Washington,  D.  C. 

August,  1907.  i 


o 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL. 


A.  ROAD  CROSSING  FAULT  TRACE  NEAR  POINT  REYES  STATION. 
Looking  southwest.  Offset,  20  feet.  Photograph  by  G.  K.  Gilbert. 


B.  FENCE  PARTED  BY  EARTHQUAKE  FAULT. 

The  fault  trace  or  fracture  accompanying  the  earthquake  is  inconspicuous,  although  the  horizontal  displace- 
ment is  considerable.  Photograph  by  G.  K.  Gilbert. 

EARTHQUAKE  EFFECTS  ALONG  THE  FAULT  TRACE. 


( 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  II 


REDWOOD  TREE  6 FEET  IN  DIAMETER  ON  LINE  OF  FAULT  SOUTH  OF  FORT  ROSS. 

The  tree  was  split  to  a height  of  35  feet,  although  the  horizontal  displacement  was  slight.  The  opening 
is  wedge-shaped  at  the  base,  runningfrom  a width  of  8 inches  on  the  side  shown  to  a fine  crack  on  the 
farther  side.  Photograph  by  Richard  L.  Humphrey. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324-  PL.  Ill 


THE  FAULT  TRACE  NEAR  POINT  REYES  STATION 

A , Looking  northwest;  B,  Looking  southeast.  Photographs  by  G.  K.  Gilbert. 


m 


. 


- 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  IV 


A.  SECONDARY  CRACKS,  SHORE  OF  BOLINAS  LAGOON. 


Photograph  by  G.  K.  Gilbert. 


Photograph  by  G.  K.  Gilbert. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  V 


RESULTS  OF  EARTH  FLOW,  NINTH  STREET,  SAN  FRANCISCO. 
Photograph  by  G.  K.  Gilbert. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  VI 


A.  SETTLING  (5  FEET)  ON  DORE  STREET,  BETWEEN  BRYANT  AND  BRANNAN  STREETS, 

SAN  FRANCISCO. 

Photograph  by  Richard  L.  Humphrey. 


B.  BUCKLING  CAUSED  BY  EARTH  FLOW,  HOWARD  STREET,  SAN  FRANCISCO. 
Photograph  by  G.  K.  Gilbert. 

EARTHQUAKE  EFFECTS  ON  MADE  GROUND. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  VII 


B 

SHIFTED  BOTTOM  OF  TOMALES  BAY. 

A,  General  view;  />,  Edge  of  new  shoal.  Photographs  by  G.  K.  Gilbert. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  VIII 


A.  EARTHQUAKE  RIDGES  ON  TIDAL  FLAT,  TOMALES  BAY. 
Photograph  by  G.  K.  Gilbert. 


B.  SLIPPING  OF  ALLUVIAL  SOIL  TOWARD  SALINAS  RIVER. 

Grain  field  adjoining  road  along  river  between  Spreckels’s  sugar  mill  and  Salinas.  Photograph  by  A.  C.  Lawson. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  IX 


B 

DAMAGE  TO  PILARCITOS  30-INCH  PIPE  LINE  BY  EARTHQUAKE. 

A,  Offset;  B,  Telescoping.  Photographs  submitted  by  Frank  Soul£. 


TRESTLE  CROSSING  THE  FAULT. 


The  slip  produced  a compression  on  the  pipe  line  which  buckled  it,  thereby  throwing  down 
the  trestle  support.  The  consequent  parting  of  the  pipe  line  suddenly  released  the  water 
from  the  pipe,  causing  a vacuum  which  brought  about  the  collapse.  Photograph  by 
Richard  L.  Humphrey. 


B.  HOUSE  ON  LINE  OF  FAULT,  TORN  ASUNDER  BY  EARTHQUAKE. 

Near  Wrights  Station,  on  Southern  Pacific  Railroad.  Photograph  by  Richard  L.  Humphrey. 


A.  COLLAPSED  PILARCITOS  30-INCH  WROUGHT-IRON  PIPE  LINE,  NEAR 


A.  RACKING  AND  SPALLING  OF  CONCRETE  PIER  DUE  TO  EARTHQUAKE.  B.  ENDURANCE  OF  CONCRETE  DAM  NEAR  FAULT  TRACE,  AT  CRYSTAL 

, , rr.  , „ ,r.  SPRINGS  LAKE,  SAN  MATEO. 

Near  south  abutment  of  Southern  Pacific  Railroad  bridge  over  Pajaro  River.  Photograph 

by  Richard  L.  Humphrey.  Photograph  by  Richard  L.  Humphrey. 


if 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324-  PL.  XII 


4.  EFFECT  OF  EARTHQUAKE  ON  THE  END  AND  THE  INSUFFICIENTLY  BRACED  CENTRAL 
PORTION  OF  A BRICK  BUILDING,  SPRECKELS’S  SUGAR  MILL,  ABOUT  4 MILES  SOUTH  OF 
SALINAS. 


Note  the  stripping  of  brick  pilasters  from  steel  columns.  Photograph  by  Richard  L.  Humphrey. 


B.  EARTHQUAKE  WRECK  OF  NEW  HALL  OF  JUSTICE,  SAN  JOSE,  BUILT  ON  ALLUVIAL  SOIL. 
Wreck  due  to  poor  quality  of  stonework  and  unnecessarily  massive  construction.  Photograph  by  Frank  Soule. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XIII 


A.  COMPARATIVE  EARTHQUAKE  ENDURANCE  OF  DISSIMILAR  STRUCTURES,  AGNEW  INSANE 

ASYLUM,  NEAR  SAN  JOSE. 

Tanks  on  steel  trestle,  undamaged,  and  circular  brick  stack,  collapsed.  Photograph  by  Richard  L.  Humphrey. 


B.  EARTHQUAKE  EFFECT,  HIGH  SCHOOL  BUILDING,  SAN  JOSE. 
Photograph  submitted  by  Frank  Soule. 


-i 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XIV 


A.  COMPARATIVE  BEHAVIOR  OF  REENFORCED  CONCRETE  AND  BRICKWORK  UNDER 
EARTHQUAKE  VIBRATION,  MUSEUM,  LELAND  STANFORD  JUNIOR  UNIVERSITY. 

The  central  portion,  of  reenforced  concrete,  was  undamaged,  but  the  brick  wings  collapsed.  Photograph  by 

Richard  L.  Humphrey. 


B.  COMPLETE  WRECK  BY  EARTHQUAKE,  COURT-HOUSE  AND  HALL  OF  RECORDS,  SANTA 

ROSA. 

Wreck  due  to  light  wooden  framing,  insufficient  bracing,  and  poor  mortar.  Photograph  submitted  by 

Richard  L.  Humphrey. 


BULLETIN  NO.  324  PL.  XV 


U.  S.  GEOLOGICAL  SURVEY 


A.  UNDAMAGED  STEEL  FRAMEWORK  SUPPORTING  DOME  OF  LIBRARY. 


B.  COLLAPSE  OF  BRICK  WALLS,  CAUSING  DESTRUCTION  OF  STEEL  SKELETON  DOME  OF 

GYMNASIUM. 

ENDURANCE  OF  STEEL  FRAMEWORK  AS  AFFECTED  BY  METHOD 
OF  SUPPORT,  LELAND  STANFORD  JUNIOR  UNIVERSITY. 


Photographs  by  Richard  L.  Humphrey. 


MEMORIAL  ARCH,  LELAND  STANFORD  JUNIOR  UNIVERSITY. 

A,  Before  the  earthquake  (photograph  submitted  by  Richard  L.  Humphrey);  B , Earthquake  effect  (photo- 
graph by  Richard  L.  Humphrey).  The  beams  designed  to  stiffen  the  walls  were  not  tied  to  them  and 
helped  to  batter  them  down  when  the  shock  came. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XVII 


A.  COLLAPSE  DUE  TO  LACK  OF  TIE  BETWEEN  WALLS  AND  FRAME,  THIELE  BUILDING 
(CEMENT  BLOCK),  PALO  ALTO. 

Photograph  by  Richard  L.  Humphrey. 


B.  COLLAPSED  TOWER  AND  GENERAL  EARTHQUAKE  WRECKAGE,  MEMORIAL  CHURCH, 
LELAND  STANFORD  JUNIOR  UNIVERSITY. 


Photograph  by  Richard  L.  Humphrey. 


U.  S.  GEOLOGICAL  SURVEY  BULLETIN  NO.  324  PL.  XVIII 


A.  EARTHQUAKE  DAMAGE  DUE  TO  LACK  OF  TIE  AND  BRACING,  GEOLOGICAL  DEPARTMENT, 
LELAND  STANFORD  JUNIOR  UNIVERSITY. 

Photograph  by  Richard  L.  Humphrey. 


B.  EARTHQUAKE  EFFECT  ON  ARCHES,  LELAND  STANFORD  JUNIOR  UNIVERSITY. 
Spalling  of  caps  and  movement  of  upper  part  of  columns.  Photograph  by  Richard  L.  Humphrey. 


U.  S.  GEOLOGICAL  SURVEY 


.4.  ENDURANCE  OF  WALLS  TIED  TOGETHER  WITH  STEEL  RODS,  LEE  BROTHERS’ 
WAREHOUSE,  SANTA  ROSA. 

Slightly  damaged  at  cornice.  The  few  blocks  which  were  thrown  down  by  the  earthquake  were  replaced 
previous  to  the  taking  of  the  photograph. 


B.  WALL  THROWN  DOWN  BY  EARTHQUAKE  VIBRATIONS-  OF  ROOF  TRUSSES  WHICH  WERE 
NOT  TIED  TO  WALL,  VANDERVOORT  BROTHERS’  LIVERY,  PALO  ALTO. 


EARTHQUAKE  EFFECTS  ON  CEMENT-BLOCK  WALLS. 

Photographs  by  Richard  L.  Humphrey. 


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1.  RACKING  OF  NEWLY  CONSTRUCTED  BUILDING,  SYNAGOGUE,  GEARY  AND  B.  GOOD  EARTHQUAKE  ENDURANCE  OF  BUTTRESSED  WALLS,  SYNAGOGUE 

FILLMORE  STREETS,  SAN  FRANCISCO.  EMANUEL,  SAN  FRANCISCO. 

Note  the  separation  of  the  brick  veneer  from  the  backing;  also  the  racking  of  the  wall  at  Photograph  submitted  by  Richard  L.  Humphrey', 

the  corner.  Photograph  by  John  Stephen  Sewell. 


X CRACKS  IN  BRICKWORK,  CAUSED  BY  ROCKING,  HOUSE  IN  SAN  B.  SLIP  OF  FOUNDATION  OF  CYCLORAMA,  STRAWBERRY  HILL,  GOLDEN 

FRANCISCO.  GATE  PARK,  SAN  FRANCISCO,  CAUSING  COLLAPSE  OF  THE  STRUCTURE. 

Photograph  submitted  by  Richard  L.  Humphrey.  . Photograph  by  Richard  L.  Humphrey. 


U.  S.  GEOLOGICAL  SURVEY  BULLETIN  NO.  324  PL.  XXIII 


A.  EARTHQUAKE  EFFECT  ON  STRUCTURE  OF  REENFORCED  CONCRETE  OF  POOR  QUALITY. 
Cyclorama,  Strawberry  Hill,  Golden  Gate  Park,  San  Francisco,  Photograph  by  Richard  L.  Humphrey. 


B.  EFFECT  OF  EARTHQUAKE  ON  ADJACENT  BUILDINGS  OF  DISSIMILAR  TYPE  AND 

CONSTRUCTION. 

Old  Mission  Dolores,  San  Francisco,  undamaged.  Tower  of  new  church  adjoining  was  so  badly  damaged 
that  it  had  to  be  taken  down.  Photograph  by  Richard  L.  Humphrey. 


— 


A.  FAILURE  OF  CAST-IRON  SHELL  OF  CONCRETE-FILLED  CAST-IRON  B.  SPALLED  GRANITE,  MARKET  STREET  ENTRANCE  OF  >£TNA  BUILDING, 

COLUMN  BY  FIRE,  ACADEMY  OF  SCIENCES  BUILDING,  SAN  FRANCISCO.  SAN  FRANCISCO. 

The  concrete  core  supports  the  load.  Note  also  the  effect  of  the  earthquake  on  the  brick  Photograph  by  Richard  L.  Humphrey, 

wall  in  the  rear.  Photograph  by  Richard  L.  Humphrey. 


u. 


!.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XXV 


A.  SUBSIDENCE  OF  STREET  IN  FRONT  OF  /ETNA  BUILDING,  SAN  FRANCISCO. 
Photograph  by  John  Stephen  Sewell. 


B.  FIRE  ENDURANCE  OF  CONCRETE,  ANNEX  OF  ACADEMY  OF  SCIENCES  BUILDING, 

SAN  FRANCISCO. 


Reenforced-concrete  floors  and  concrete-filled  cast-iron  columns  with  plaster  covering.  Photograph  by 

Richard  L.  Humphrey. 


BULLETIN  NO.  324  PL.  XXVI 


BUCKLED  COLUMNS  AND  COLLAPSED  FLOOR  PANEL,  B.  INCIPIENT  FAILURE  OF  NAKED  CAST-IRON  COLUMN  IN  CITY 

BULLOCK  & JONES  BUILDING,  SAN  FRANCISCO.  HALL,  SAN  FRANCISCO. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XXVII 


A.  EARTHQUAKE  ENDURANCE  OF  REENFORCED-CONCRETE  BUILDING,  BEKINS  VAN  AND 
STORAGE  COMPANY’S  WAREHOUSE,  SAN  FRANCISCO,  UNDER  CONSTRUCTION. 

The  only  building  of  pare  reenforced-concrete  type  in  the  city.  The  brick  walls  composing  the  shell  of  the 
building  were  cracked,  but  the  reenforced-concrete  floors  and  columns  were  uninjured.  Photograph  by 
Richard  L.  Humphrey. 


B.  FAILURE  OF  TERRA-COTTA  COLUMN  COVERINGS,  RESULTING  IN  BUCKLED  COLUMNS; 
ENDURANCE  OF  CINDER-CONCRETE  FLOORS;  CENTER  OF  GROUND  FLOOR,  ARONSON 
BUILDING,  SAN  FRANCISCO. 


Photograph  by  Richard  L.  Humphrey. 


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U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XXVIII 


A.  EARTHQUAKE  ENDURANCE  OF  A WELL-CONSTRUCTED  BRICK  BUILDING:  APPRAISERS’ 
WAREHOUSE,  SAN  FRANCISCO. 

The  walls  were  built  with  full-header  courses  and  show  only  a few  slight  cracks,  although  the  building 
was  located  on  alluvial  soil.  Photograph  by  Richard  L.  Humphrey. 


B.  FAILURE  OF  ORNAMENTAL  TERRA  COTTA,  CROCKER  ESTATE  BUILDING,  SAN  FRANCISCO. 

This  terra  cotta  failed,  though  solidly  filled  with  brick  mortar.  The  damage  shown  was  probably  due  to  fire, 
although  damage  of  this  kind  was  caused  by  both  earthquake  and  fire.  Photograph  by  John  Stephen 
Sewell. 


( 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XXIX 


A.  EARTHQUAKE  CRACKS  IN  WALL  OF  VAULT,  CALIFORNIA  CASKET 
COMPANY’S  BUILDING,  SAN  FRANCISCO. 

Photograph  by  Richard  L.  Humphrey. 


B.  COLLAPSE  OF  FLOOR  PANEL,  CAUSED  BY  LOAD  FALLING  FROM  A FLOOR  ABOVE,  THIRD 
FLOOR  OF  /ETNA  BUILDING,  SAN  FRANCISCO. 

The  failure  of  the  upper  floor  was  due  to  the  softening  by  heat  of  reenforcing  steel  bands.  Photographs 

by  Richard  L.  Humphrey. 


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U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XXXII 


COMPLETE  FAILURE  OF  SLOW-BURNING  WOOD  CONSTRUCTION, 
THE  EMPORIUM,  SAN  FRANCISCO. 


A large  department  store.  A,  Interior  (photograph  by  John  Stephen  Sewell);  B,  Exterior  (photograph 

by  Richard  L.  Humphrey). 


BUCKLING  OF  COLUMNS  DUE  TO  FAILURE  OF  PLASTERED  METAL-LATH  FIREPROOFING,  FAIRMOUNT  HOTEL,  SAN  FRANCISCO. 

The  method  of  fireproofing  was  to  inclose  the  column  between  the  metal  lath  forming  the  partitions.  Photographs  by  Richard  L,  Humphrey. 


U.  S.  GEOLOGICAL  SURVEY  BULLETIN  NO.  324  PL.  XXXV 


A.  INCIPIENT  BUCKLING  OF  COLUMNS  FROM  HEAT,  FIRST 
STORY,  JAMES  FLOOD  BUILDING,  SAN  FRANCISCO. 


The  brick  filling  probably  saved  the  columns  from  fatal  buckling 
or  collapse.  Photograph  by  John  Stephen  Sewell. 


B.  FAILURE  OF  SUSPENDED  CEILING,  HALL  OF  JUSTICE,  SAN  FRANCISCO. 
Photograph  by  Richard  L.  Humphrey. 


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U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XXXVII 


A.  STONEWORK  SPALLED  BY  FIRE,  HIBERNIA  SAVINGS  AND  LOAN  SOCIETY’S  BUILDING, 

SAN  FRANCISCO. 


Photograph  by  Richard  L.  Humphrey. 


B.  EARTHQUAKE  DAMAGE,  JACKSON  BREWING  COMPANY'S  BUILDING,  SAN  FRANCISCO. 

Light  walls,  badly  bonded  and  laid  up  with  poor  lime  mortar,  and  flimsily  constructed  steel  work.  Photograph 

by  Richard  L.  Humphrey. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XXXVIII 


A.  GOOD  EARTHQUAKE  ENDURANCE  OF  A BUILDING  OF  THE  MONUMENTAL  TYPE:  UNITED 
STATES  MINT,  SAN  FRANCISCO. 

Showing  only  slight  damage  to  brick  stack,  probably  due  to  earthquake.  Photograph  by  John  Stephen 

Sewell. 


B.  SPALLING  OF  STONEWORK  BY  FIRE,  NORTHWEST  FRONT  OF  UNITED  STATES  MINT.. 
Photograph  by  Richard  L.  Humphrey. 


U.  8.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XXXIX 


A.  WRECKED  TOWER  AND  SPALLED  STONEWORK,  HALL  OF  JUSTICE,  SAN  FRANCISCO. 
Photograph  by  John  Stephen  Sewell. 


B.  COMPLETE  WRECK  BY  EARTHQUAKE,  DUE  TO  POOR  DESIGN,  MAJESTIC  THEATER, 

SAN  FRANCISCO. 

Photograph  by  Richard  L.  Humphrey. 


. SPALLING  OF  ENAMELED  BRICK  IN  LIGHT  WELL,  AND  FAILURE  OF  B.  BUCKLING  OF  BASEMENT  COLUMN  DUE  TO  FAILURE  OF  TERRA- 
FIREPROOFING OF  WINDOW-FRAME  SEPARATORS,  MERCHANTS'  COTTA  COVERING  IN  FIRE,  MILLS  BUILDING,  SAN  FRANCISCO. 

EXCHANGE  BUILDING,  SAN  FRANCISCO.  Photograph  by  Richard  L.  Humphrey. 

Photograph  by  Richard  L.  Humphrey. 


L.  ENDURANCE  OF  A WELL-PROTECTED  BUILDING  SUBJECTED  TO  SEVERE  B.  WARPING  OF  PLASTERED  METAL-LATH  COVERING  BY  FIRE,  MURPHY 

HEAT,  MAIN  EXCHANGE  OF  PACIFIC  STATES  TELEPHONE  AND  TELEGRAPH  BUILDING,  SAN  FRANCISCO. 

COMPANY,  SAN  FRANCISCO.  Photograph  by  Richard  L.  Humphrey. 

Rolling  shutters,  self-supporting  brick  walls,  concrete  floors,  and  concrete  protection  for 
columns  and  girders.  Photograph  by  Richard  L.  Humphrey. 


-( 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XLII 


A.  ROOF  TRUSSES  DAMAGED  BY  HEAT,  THROUGH  FAILURE  OF  TERRA-COTTA  COVERING, 
MUTUAL  LIFE  BUILDING,  SAN  FRANCISCO. 

Photograph  by  Richard  L.  Humphrey. 


B.  EFFECT  OF  SETTLING  OF  GROUND  SUBJECTED  TO  EARTHQUAKE  VIBRATIONS, 
STEEL-FRAME  BUILDING  UNDER  CONSTRUCTION. 


The  concrete  basement  walls  were  not  reenforced.  Post-office  in  the  background.  Photograph  by 

Richard  L.  Humphrey. 


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U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XLIII 


A.  CRACKS  IN  MASONRY,  PAVILION  OF  POST-OFFICE,  SAN 
FRANCISCO. 

The  window  reveal  and  sill  were  jostled  together  by  the  earthquake  at  the 
point  indicated  by  the  arrow.  Photograph  by  John  Stephen  Sewell. 


B.  EFFECT  OF  SLIP,  MISSION  STREET,  SAN  FRANCISCO. 

Corner  of  post-office  building  at  the  left.  Photograph  submitted  by  Richard  L.  Humphrey. 


U.  S.  GEOLOGICAL  SURVEY  BULLETIN  NO.  324  PL.  XLIV 


A.  CRACKS  IN  MASONRY  AND  SETTLING  OF  OUTER  TERRACE,  POST-OFFICE  BUILDING, 

SAN  FRANCISCO. 


The  surface  of  the  street  went  down  at  this  point  at  least  4 feet.  Photograph  by  John  Stephen  Sewell. 


B.  EFFECT  OF  EARTHQUAKE  IN  LOOSENING  STONEWORK,  NORTHEAST  FACE  OF 


POST-OFFICE  BUILDING. 


Photograph  by  Richard  L.  Humphrey. 


U.  S.  GEOLOGICAL  SURVEY 


EULLETIN  NO.  324  PL.  XLV 


B 


FAILURE  OF  HOLLOW  TERRA-COTTA  TILE  FIREPROOFING. 

4,  First  story  of  Spring  Valley  Water  Company’s  Building,  San  Francisco  (photograph  by  John  Stephen  Sewell); 
B,  Mills  Building,  San  Francisco  (photograph  by  Richard  L.  Humphrey).  The  lower  webs  of  the  floor  tiles 
were  spalled  or  taken  entirely  off  by  the  fire. 


U.  S.  GEOLOGICAL.  SURVEY 


BULLETIN  NO.  324  PL.  XLVI 


A.  brickwork  thrown  down  by  earthquake  vibration, 

TOWER  OF  UNION  FERRY  BUILDING,  SAN  FRANCISCO. 

Note  bending  of  time-ball  shaft.  Photograph  submitted  by  Richard  L. 
Humphrey. 


B.  EFFECT  OF  SEVERE  SHAKING  ON  WELL-BONDED  BRICKWORK  FILLED  WITH  GOOD 
MORTAR,  TOWER  OF  UNION  FERRY  BUILDING. 

Note  sagged  tie-rod,  stretched  by  the  racking  of  the  structure.  Photograph  by  John  Stephen  Sewell. 


SHEARED  RIVETS,  TOWER  OF  UNION  FERRY  BUILDING,  SAN  FRANCISCO. 

A,  In  column  cover  plate;  B,  In  diagonal  connection.  Photographs  by  Richard  L.  Humphrey, 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL.  XLVIII 


A.  BUCKLING  OF  BASEMENT  COLUMN  DUE  TO  FAILURE 
OF  PLASTERED  METAL-LATH  FIREPROOFING,  RIALTO 
BUILDING,  SAN  FRANCISCO. 

Photograph  by  Richard  L.  Humphrey. 


B.  DAMAGE  SAID  TO  HAVE  BEEN  CAUSED  BY  DYNAMITE,  RIALTO  BUILDING. 
Photograph  by  John  Stephen  Sewell. 


-( 


GEOLOGICAL  SURVEY 


FAILURE  OF  BASEMENT  COLUMN  DUE  TO  FIRE,  SLOANE  BUILDING,  B.  FAILURE  OF  TERRA-COTTA  TILING  AND  METAL-FRAME  WIRE-GLASS  WIN- 

SAN  FRANCISCO.  DOWS  BY  FIRE,  LIGHT-WELL  COLUMN,  WELLS-FARGO  BUILDING,  SAN 

FRANCISCO. 

Photograph  by  John  Stephen  Sewell.  Photograph  by  Richard  L.  Humphrey. 


m, 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  NO.  324  PL. 


A.  COLLAPSE  OF  BUILDING  DUE  TO  BUCKLING  OF  COLUMNS,  SPRING  VALLEY  WATER 
COMPANY’S  BUILDING,  SAN  FRANCISCO. 

Photograph  by  Richard  L.  Humphrey. 


B.  FAILURE  OF  TERRA-COTTA  TILE  COVERING  IN  FIRE,  UNION  TRUST  COMPANY’S 
BUILDING,  SAN  FRANCISCO. 


Photograph  by  Richard  L.  Humphrey. 


U.  S.  GEOLOGICAL  SURVEY 


A.  AN  UNFINISHED  STEEL  SKELETON,  WITH  NONFIREPROOFED  STEEL  WORK. 


B.  UNPROTECTED  STEEL  FRAME  AND  GENERAL  FLIMSY  CONSTRUCTION,  COWELL  BUILDING. 

EFFECTS  OF  HEAT  ON  STEEL  WORK,  SAN  FRANCISCO. 

Photographs  by  Richard  L.  Humphrey. 


U.  S.  GEOLOGICAL  SURVEY  BULLETIN  NO.  324  PL.  Lll 


A.  ENDURANCE  OF  BRICK  VAULT. 

This  vault,  which  was  in  the  original  Wells-Fargo  Building,.  San  Francisco,  passed  the  fire  test  satisfactorily, 
although  the  building  was  completely  destroyed.  Note  the  defective  steel  "fireproof”  safes  near  by. 
Photograph  by  Richard  L.  Humphrey. 


B.  ABSOLUTE  FAILURE  OF  SO-CALLED  "FIREPROOF”  SAFES. 

the  rear  are  the  Palace  Hotel  fat  the  left)  and  the  Crocker  Building  (at  the  right).  Photograph  by 
-Richard  L.  Humphrey. 


A.  EARTHQUAKE  DAMAGE  TO  BRICK  STACK  OF  STAR  SEC- 
TION, VALENCIA  STREET  POWER  STATION,  SAN  FRANCISCO. 

Showing  peculiar  crack  in  reentrant  angle.  Photograph  by  Richard 
L.  Humphrey. 


B.  GENERAL  EARTHQUAKE  EFFECT  ON  FRAME  BUILDINGS  SITUATED  ON  ALLUVIAL  SOIL, 
HOWARD  STREET,  SAN  FRANCISCO. 


Photograph  by  A.  C.  Lawson 


GEOLOGICAL  SURVEY 


DESTRUCTION  BY  FIRE,  SAN  FRANCISCO. 

View  looking  west  from  Telegraph  Hill,  showing  unburned  houses  on  summit  of  Russian  Hill.  St.  Francis  Roman  Catholic  Church,  with  its  excellent  brick  walls,  in  the  foreground.  Photograph 

submitted  by  Frank  Soule, 


J.  S.  GEOLOGICAL  SURVEY 


of  principal  buildings  in  the  < 


iisai  lisir- 


jet.  Photograph  by  John  Stephen  Sewell. 

HL  wtM 


MAP  OF  SAN  FRANCISCO  SHOWING  BURNED  DISTRICT;ACCOMPANFING  REPORT  OF  RICHARD  L.  HUMPHREY. 


Principal  distribution  mains. 
Salt-water  system. 

Old  shore  line. 

Boundary  line  of  burned  district. 
Principal  earthquake  breaks  in  streets. 


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